SBC CAN-Functions on Classic PCDs Owner's manual

Brand: SBC

Model: CAN-Functions on Classic PCDs

Type: Owner's manual

Document 26-839 │ Edition ENG05 │ 2019-05-27

Manual

CAN-Functions on PCD2.M5_ & PCD3

CPU Serie Classic

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Content

0-1

0 Content

0.1 Document History .................................................................................. 0-3

0.2 About this manual .................................................................................. 0-3

0.3 Brands and trademarks ........................................................................ 0-3

1 Introduction

1.1 CAN2.0Specication(DataLinkLayer) ................................................ 1-3

1.2 Properties .............................................................................................. 1-3

1.3 Frame types ........................................................................................... 1-5

1.4 Messageacceptanceltering ................................................................ 1-6

2 Hardware

2.1 Communication interfaces .................................................................... 2-1

2.1.1 For the PCD3.M6240, PCD3.M6340 and PCD3.M6360 ....................... 2-1

2.1.2 CAN bus attachment, module PCD7.F7400 for the PCD2.M5x40 ........ 2-2

2.2 CAN Connection ................................................................................... 2-3

2.2.1 Pin signal description ............................................................................. 2-3

2.2.2 Connections and cabling ....................................................................... 2-3

2.2.3 Maximum distance of the network ......................................................... 2-4

2.2.4 Shielding ................................................................................................ 2-4

2.3 Port ID Table for CAN Interfaces ........................................................... 2-4

3 Function

3.1 General .................................................................................................. 3-1

3.2 CAN Direct Access ................................................................................ 3-3

3.2.1 General .................................................................................................. 3-3

3.2.2 Polling vs interrupts ............................................................................... 3-3

3.2.3 Remote transmission requests RTR ...................................................... 3-3

3.2.4 Initialisation sequence ........................................................................... 3-3

3.2.5 Self-received frames .............................................................................. 3-3

3.3 CAN Basic Services............................................................................... 3-4

3.3.1 General .................................................................................................. 3-4

3.3.2 Remote transmission requests RTR ...................................................... 3-4

3.3.3 Initialisation sequence ........................................................................... 3-4

3.4 CAN Data Mapping ................................................................................ 3-5

3.4.1 General .................................................................................................. 3-5

3.4.2 CAN process image ............................................................................... 3-5

3.4.3 Conguration ......................................................................................... 3-5

3.4.4 Data transfer .......................................................................................... 3-6

3.4.5 Remote transmission requests RTR ...................................................... 3-6

3.4.6 Initialisation sequence ........................................................................... 3-6

3.5 Simultaneoususeofdierentoperatingmodes .................................... 3-7

3.5.1 General .................................................................................................. 3-7

3.5.2 Priorities ................................................................................................. 3-7

3.5.3 Reception .............................................................................................. 3-7

3.5.4 Transmission ......................................................................................... 3-7

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Content

0-2

4 CongurationandProgramming

4.1 System Functions .................................................................................. 4-1

4.1.1 Polling vs interrupts ............................................................................... 4-2

4.1.2 Conguration ......................................................................................... 4-2

4.1.3 Initialisation sequence ........................................................................... 4-3

4.1.4 Overview operating options ................................................................... 4-3

4.1.5 PLCStates............................................................................................. 4-3

4.2 User interface ........................................................................................ 4-4

4.2.1 General .................................................................................................. 4-4

4.2.2 Data Registers ....................................................................................... 4-6

4.2.3 CAN Direct Access ................................................................................ 4-7

4.2.4 CAN Basic Services............................................................................... 4-12

4.2.5 CAN Data Mapping ................................................................................ 4-15

4.3 Conguration ......................................................................................... 4-16

4.3.1 StartingtheCongurator ....................................................................... 4-16

4.3.2 Data Mapping ........................................................................................ 4-17

4.4 Programmingmodel(CANDirectAccess)............................................. 4-18

4.4.1 Transmission ......................................................................................... 4-18

4.4.2 Reception .............................................................................................. 4-19

A Appendix

A.1 Icons ...................................................................................................... A-1

A.2 Contact ................................................................................................. A-2

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Content

0-3

0.1 DocumentHistory

Date Version Changes/Remarks

2005-12-15 EN01 Published Edition

2009-09-09 EN02 ModicationsforPCD2.M5_

2013-09-30 EN03 NewLogoandnewcompanyname

2014-06-20 EN04 3 types of PCD3 with CAN

2019-05-27 ENG05 Newphonenumber:(2015-02-15)

0.2 Aboutthismanual

See the section in the appendix in relation to some of the terms, abbreviations and

the references used in this manual.

0.3 Brandsandtrademarks

Saia PCD

and Saia PG5

are registered trademarks of Saia-Burgess Controls AG.

Technicalmodicationsarebasedonthecurrentstate-of-the-arttechnology.

Saia-Burgess Controls AG, 2005.

Published in Switzerland

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Introduction

1-1

CAN2.0Specication(DataLinkLayer)/Properties

1 Introduction

This document gives an introduction and general description of the Saia PCD

with

CANinterface,aswellasthespecicfunctionsoftheClassicuserinterface.The

Hardware as well as the basic functionality is explained. Two systems are provided: a

Classic version and a xx7 version.

TheprovidedCANfunctionalityisaLayer-2interface.Theuserisgivenachoiceof

severaloperatingmodesprovidingdierentlevelsofcomfortandfunctionality.All

functionality is accessed with System Functions by the user.

The CAN interface does not provide any CANopen functionality. However it is possi-

bletoaccesstosimplerCANopenslavesthroughthegivenLayer-2interface.Thisre-

quires the user to implement all the relevant CANopen messages himself in the user

programusingtheprovidedLayer-2interface.

There are three types of PCD3 with CAN-bus. The two types PCD3.M6240 and

PCD3.M6340 are no longer fabricated. They were replaced with the PCD3.M6360,

which is faster and has more storage capacity.

ForthePCD2.M5x40weoerthecardPCD7.F7400.

These three PCD3s with CAN-fonction as well as the card PCD7.F2400 are OEM-

products and appear neither in the system catalogue nor in the price list.

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Introduction

1-2

CAN2.0Specication(DataLinkLayer)/Properties

OverviewofthePCD3-typeswithCAN-fonction:

TechnicaldataCPUs

PCD3.M6240 PCD3.M6340 PCD3.M6360

CAN

Numberofinputs/outputs

orI/Omoduleslots

1023

Expansion connection

yes

Processing time [µs] ■ bit operation

■ word operation

0.3…1.5 µs

0.9 µs

0.1…0.8 µs

0.3 µs

Integrated Web server + USB +

Date-time(RTC)

yes

On-boardmemory

Usermemory(RAM)

1MByte 2MBprog.+1MBtext/

(ashmemory)

Backupmemoryash

1MByte(onboard)

Flashlesystem

- 16 MByte

Data backup

1…3yearswithLithiumbattery

Optionalmemory up to 4 GByte

On-boarddatainterfaces 4…5

RS-485onterminalblock(Probus-DP

slave,Pro-S-Net(S-IO,S-Bus))

upto115.2kBit/sor

Pro-S-Netupto187.5kBit/s

USB 1.1

no yes

Ethernet-TCP/IP10/100MBit/s

yes

RS-232upto115.2kBit/s

yes(onD-Sub)

RS-422/RS-485onPort#3

Probus-DPslave,Pro-S-Net

(S-IO,S-Bus),upto1.5MBit/s

ControllerAreaNetwork(CAN2.0B)

yes(onD-Sub)

Profibus-DPMasterupto12MBit/s

Optionaldatainterfaces Up to 8

OptionalPCD3.F1xx modulesfor

RS-232, RS-485, RS-422, TTY/20mA

and Belimo MP-Bus

onlySlot#0

OptionalPCD3.F2xx modulesfor

RS-232, RS-485, RS-422, TTY/20mA

and Belimo MP-Bus

Slot#0…3upto8ports

General

Supply voltage

(accordingtoEN/IEC61131-2)

24VDC/˗20/+25%max.incl.5%ripple

Capacity5V/24Vintern

max.600mA/100mA

Programmable

from PG5

Version $1.3.100

from PG5

Version $2.0.136

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Introduction

1-3

Frame types

1.1 CAN2.0Specication(DataLinkLayer)

TheControllerAreaNetwork(CAN)isaserialcommunicationsprotocolwhichef-

cientlysupportsdistributedreal-timecontrolwithaveryhighlevelofsecurity.This

chaptergivesashortsummaryofthemostrelevantfeaturesdenedintheCAN

specication.Formoredetailstoanysubjectpleaserefertowww.can-cia.org.

TheCANspecicationisdividedintwoparts:partAandpartBwherepartBdoes

alsoincludeandsupportallfeaturesofpartA.Themostimportantdierencebetween

thetwopartsconcernstheformatofthemessageidentier

Specication Message ID format

CAN2.0 A Standard 11 bits

CAN2.0 B Extended 29 Bits

Messages in both formats can coexist on the same network.

CAN implementations that are designed according to part A, and CAN implementa-

tionsthataredesignedaccordingtopartBoftheCAN2.0specicationcancommuni-

cate with each other as long as it made no use of the extended format.

1.2 Properties

Messageproperties

Informationonthebusissentinxedformatmessagesofdierentlength.CANsup-

ports messages of up to 8 bytes data. Standard end extended message ID formats

are possible.

Busproperties

TheCANbussupportsbitratesofupto1MBit/s.Dierentbitratesfrom10kBit/sto

1MBit/sarerecommendedwhilethesupportfor20kBit/sismandatory.

TheCANspecicationprescribesseveralerrordetectionmechanisms.Errorcoun-

ters and indicators allow a permanent control of the bus condition. Defect nodes are

automaticallyswitchedo.

Informationrouting

ACANnodedoesnotmakeuseofanyinformationaboutthesystemconguration.

Forinstance,noexplicitstationaddressesaredened.

Theidentierofamessagedoesnotindicatethedestinationofthemessagebut

describesthemeaningofthedata.Thus,everynodecandecidebymessageltering

whether the received data requires any action or not.

This mechanism allows multicast reception with time synchronization.

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Introduction

1-4

Messageacceptanceltering

Priorisationandarbitration

Theprioritiesofmessagesaredenedbytheiridentier.Messageswithloweridenti-

erhavehigherpriority.

Any connected unit may start to transmit a message whenever the bus is idle. If 2

ormoreunitsstarttransmittingmessagesatthesametime,thebusaccessconict

isresolvedbybitwisearbitrationusingthemessageidentier.Themechanismofarbi-

tration guarantees that neither information nor time is lost.

Adataframeprevailsoveraremoteframe(RTR).Ifatransmittedmessageiscor-

rupted, an automatic retransmission will take place according to the message priority.

Bittiming

The nominal bit time is divided into separate non-overlapping time segments. The

length of each segment is described in so-called time quanta units. The chosen divi-

sion of one bit time into time quanta is directly related to the generation of the bit rate.

Theratiobetweenthedierenttimesegmentsdenesthesamplepointofonebit.

Thecorrectdenitionofthesamplepointdependsonthenetworktopology.Theposi-

tion of the sample point should be the same for all devices connected to the same

network.

Thedierentsegmentsaredenedasfollows:

Nominal Bit Time

SYNC_SEG PROP_SEG PHASE_SEG1 PHASE_SEG2

Sample Point

Segment Length

SYNC_SEG   1TIMEQUANTUM

PROP_SEG   1,2,...,8TIMEQUANTA

PHASE_SEG1  1,2,...,8TIMEQUANTA

PHASE_SEG2  max(PHASE_SEG1;InformationProcessingTime)

INFORMATION  <=2TIMEQUANTA

PROCESSING TIME

TimeSegment1

The sum of the propagation and phase segment 1 is commonly denoted as Time

Segment1andisusedinmanyCANcontrollersforcongurationofthebittiming.

Thepropagationandphasesegment1canthennotbeconguredseparatelyany-

more. However, this is not required anyway since the sample point is located between

the two phase segments.

TIME_SEG1=PROP_SEG+PHASE_SEG1

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Introduction

1-5

Messageacceptanceltering

1.3 Frametypes

Dataframe

Adataframeconsistsofseveralxedformateldsandupto8bytesdata.Thefollow-

ing image gives an overview of the data frame format.

A data frame can be sent by any node at any time. The transmission is dependent on

the arbitration process.

Remoteframe

By sending a remote frame a node requiring data may request another node to send

thecorrespondingdataframe(RemoteTransmissionRequest,RTR).Thedataframe

andthecorrespondingremoteframearenamedbythesamemessageidentier.

ThepolarityoftheRTRbitinthearbitrationeldindicateswhetheratransmitted

frame is a data frame or a remote frame. A remote frame contains no data.

Identier

Thefollowingimageshowsthedierentbitswithinthearbitrationeld(includingthe

messageidentier).ItcontainstheIDE-bitindicatingtheformatoftheidentierand

the RTR bit indicating the frame type.

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Introduction

1-6

Messageacceptanceltering

1.4 Messageacceptanceltering

EveryCANnodeimplementsamessageacceptancelteringmechanismthatallows

receivingonlyadenedrangeofmessageidentierswhileexcludingthereceptionof

anymessageidentiersoutsideofthisrange.DependingontheusedCANcontroller,

severalrangesmaybedened.

Thelteringisbasedontheuseofaconguredidentierandaltermask.Ames-

sageisacceptedforreceptionintothebuerifthefollowingconditionistrue:

(ReceivedMsgIDXORConguredMsgID)AND Mask = 0

Twospecialcasescanbederivedfromthiscondition(exampleforstandard11bit

identiers):

Mask Condition

0x000 Any message ID is accepted for reception

0x7FF OnlytheconguredmessageIDisacceptedforreception

Inthegeneralcaseeverybitofthemaskthatissetto0speciestherespectivebitof

theincomingmessageidentiertobe«don’tcare»foridentiermatching.Thefollow-

ingexampleillustratesthemessagelteringinthegeneralcaseforstandard11bit

identiers:

Hex 10 9 8 7 6 5 4 3 2 1 0

Acceptance ID 0x137 0 0 1 0 0 1 1 0 1 1 1

AcceptanceMask 0x7EC 1 1 1 1 1 1 0 1 1 0 0

ReceivedIdentiers 0 0 1 0 0 1 X 0 1 X X

0x124 0 0 1 0 0 1 0 0 1 0 0

0x125 0 0 1 0 0 1 0 0 1 0 1

0x126 0 0 1 0 0 1 0 0 1 1 0

0x127 0 0 1 0 0 1 0 0 1 1 1

0x134 0 0 1 0 0 1 1 0 1 0 0

0x135 0 0 1 0 0 1 1 0 1 0 1

0x136 0 0 1 0 0 1 1 0 1 1 0

0x137 0 0 1 0 0 1 1 0 1 1 1

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Hardware

2-1

Characteristic | Interface

2 Hardware

2.1 Communicationinterfaces

2.1.1 ForthePCD3.M6240,PCD3.M6340andPCD3.M6360

ControllerAreaNetwork(CAN)

RS232/PGU

Port 0

CAN(9-poleD-Subsocket)

Port 10

D-Sub

Signal D-Sub

Signal Explanation

1 DCD 1 nc not connected

2 RXD 2 CAN_L* Receive/transmitdatanegative

3 TXD 3 GND* 0 V Data communication potent.

CAN Ground

4 DTR 4 nc not connected

5 GND 5 nc not connected

6 DSR 6 GND* 0 V Data communication potent.

Notconnectedonprototypes!

7 RTS 7 CAN_H* Receive/transmitdatapositive

8 CTS 8 nc not connected

9 nc 9 nc not connected

Port 0 Port 10

Galvanic isolated signals

For all types

Terminal block for supply, watchdog, interrupt inputs

and Port 2

Probus

signal

Probus

wiring

Pin Signal Explanation

1 D

Port 2; RS-485 up to 115 kbps

usable as free user interface

orProSBCS-Busupto

187.5 kbps

RxD/TxD-N

green

2 /D RxD/TxD-P

red

3 Int0 2 interrupt inputs or

1 fast counter

4 Int1

5 WD

Watchdog

6 WD

7 +24V

Power supply

8 GND

RS-485 terminator switch

Switch

position

Designation Explanation

left O without termination resistors

right C with termination resistors

PCD3.M6xxx is a CPU that provides a galvanic isolated high-speed CAN interface.

TheCPUhasthesamefunctionsasaPCD3.M554xexceptthattheSBCS-Net/MPI

interfaceisreplacedbyCANfunctionality.Thisdocumentonlyspeciesdierences.

Please refer to existing PCD3.M554x documentation for common features.

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Hardware

2-2

Characteristic | Interface

2.1.2 CANbusattachment,modulePCD7.F7400forthePCD2.M5x40

The CAN Interface PCD7.F7400 provides a galvanic isolated high-speed CAN

interfacewithupto1MBit/s.TheCANbusshouldbeconnecteddirectlytothe

PCD7.F7400 module.

PCD7.F7400

toconnecttheCANbus, 1MBit/s

CANSpecications: CAN2.0B

Isolation:   GalvanicisolationforCAN_LandCAN_H

Port: 8

PCD7.F7400

ControllerAreaNetwork(CAN)

CAN(9-poleD-Submale)onslotC

Port 8

D-Sub

Signal Explanation

1 nc not connected

2 CAN_L* Receive/transmitdatanegative

3 GND* 0 V Data communication potent.

CAN Ground

4 nc not connected

5 nc not connected

6 GND* 0 V Data communication potent.

7 CAN_H* Receive/transmitdatapositive

8 nc not connected

9 nc not connected

Galvanic isolated signals

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Hardware

2-3

Characteristic | Interface

2.2 CANConnection

2.2.1 Pinsignaldescription

CAN interface is the male D-Sub 9 on the right. Pin numbering is top view.

The Pinout is compliant to CiA Draft Standard 102 Revision 2.0.

ThisstandarddenestheCANPhysicalLayerforIndustrialApplicationsandisavail-

able for free on the Internet: www.can-cia.org

CAN(Port10) Pin CiAStandard102 SBCwiring

1 Reserved not connected

2 CAN_Lbusline(dominantlow) CAN_Lbusline(dominantlow)

Galvanic isolated

3 CAN_GNDCANGround CAN_GNDCANGround

Galvanic isolated

4 Reserved not connected

5 (CAN_SHLD)OptionalCANShield not connected

6 (GND)OptionalCANGround CAN_GNDCANGround

Galvanic isolated

Notconnectedonprototype!

7 CAN_Hbusline(dominanthigh) CAN_Hbusline(dominanthigh)

Galvanic isolated

8 Reserved(errorline) not connected

9 (CAN_V+)OptionalCANexternal

positive supply

not connected

D-SubangeisconnectedtometallicPCD3Backplate.

Nobusterminationresistorisprovided.Nominal120Ωresistorsmustbeplaceatbothextremitiesof

thecablebetweenCAN_LandCAN_Hsignals.

2.2.2 Connectionsandcabling

Commercial bus couplers having an integrated bus termination are available and al-

low to build a network that is not disrupted impedance match in case of unconnected

cable.

Example of CAN bus coupler:

ERNI ERbic CAN BUS

Other manufacturers like Delconec or FCT also provide CAN bus couplers.

AccordingtoISO11898Norm,Cablelineimpedancemustbe120Ω.

ForCANcablingtheuseoftwistedpaircable(2x2)havinganimpedanceof

108...132Ωisrecommended.

Example of rigid cable: www.intercond.com

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Hardware

2-4

Characteristic | Interface

2.2.3 Maximumdistanceofthenetwork

The maximum length of a CAN network is not only limited by signal levels but also by

its delay. A bit-to-bit arbitration is done in the addressing phase and the issuer needs

to listen to the answer on the cable to know if it grants the bus. This answer has to

reach(delay)theissuerinonebittime.

At1MBit/s,itistheoreticallypossibletoreachalengthof40m.

However this 40 m distance is only possible with a non-isolated solution. With a

galvanicisolatednode,anadditionaldelayoccursinthedatapathoftheinsulator(in

ourcase15to55nsineverydirection).

At1MBit/s,thisreducesthemaximumlengthtoabout22m.(Assumedeachmeter

cablehasadelayofabout5ns).

Slower speeds also have a reduction of their maximum length but this is less rel-

evant.

Possible baud rates and approximate cable length:

Baud rate in Bit 10k 20k 50k 100k 125k 250k 500k 1M

Total maximum

length in m

5000 2500 1000 500 500 250 100 18

Maximum Stub

length in m

Distances over

1000 m with

repeater(s)samelimits

as 50 kbits

< 50 < 20 < 20 < 10 < 5 < 1

Sum length of all

stubs

max.

250 m

max.

100 m

max.

100 m

max. 50

max. 25

max.

5 m

Never put a bus termination at the end of one stub.

ACANnetworkrequiresa120Ωtermination(betweenCAN_LandCAN_H)at

bothendsofthenetworkevenforshortdistances.

2.2.4 Shielding

Shielded cable is necessary because High-speed CAN signal edges can not be lim-

ited to avoid electromagnetic pollution.

Shielding is also required for lower baud-rates.

Shieldingcanbeconnectedatbothendsoratjustoneendbutatleastatoneplace.

CAN galvanic isolation: minimum 500 V

Number of supported nodes: 64

2.3 PortIDTableforCANInterfaces

PCD3.M6360 Port 10

PCD3.M6340 Port 10

PCD3.M6240 Port 10

PCD2.M5x40 with PCD7.F7400 Port 8

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Function

General

3-1

3 Function

3.1 General

CANLayer-2

TheCANcontrolleronthePLCextensionimplementsaCANLayer-2accesstothe

bus.AllLayer-2protocolhandlingisperformedbythecontroller.Theusercangivea

message to the controller and specify when it is sent. The user can also specify which

messages are to be received by the controller and read the messages out of the con-

troller memory after reception.

Operatingmodes

TheCANcontrollerprovidesseveralbuers(messageobjects)whichcanbefreely

conguredastransmissionorreceptionbuersforanymessageID.Theuserispro-

videdwiththreedierenttypesofaccessestothecontrollerfunctionality:

● CAN Direct Access (FullCAN):directhardwareaccesstoall32buers.The

 usercanindependentlyaccessall32buers.Anextensiveinterfaceprovides

all functionality integrated in the CAN controller. This mode is analogue to the

FullCAN principle implemented in the controller itself.

● CAN Basic Services (BasicCAN):oneTransmitandoneReceiveQueue

allow a simpler handling of CAN communication in the user program. Several

 messagescanbesentthroughthequeuewithoutwaitingfortheconrmation

of each message. The receive queue ensures that no messages are lost on

 reception(ifthequeuedepthisdesignedaccordingly).Theuserinterfaceis

 considerablysimpliedincomparisontotheCANDirectAccess.Thismodeis

analogue to the BasicCAN principle implemented in several simple CAN cont

rollers with only one receive and one transmit path.

● CAN Data Mapping: the data mapping does simplify and automate the cyclic

 exchangeofprocessdata.Thismappingisconguredatstart-upwiththemes

sage IDs to be handled. The message data is directly mapped to process data

 ofthePLC.Alloutputmessagesareautomaticallysentbythedatamanagerin

 aspeciedinterval.Thereceivedmessagesaremappedtotheprocessdataby

the manager.

The three modes can be used simultaneously with some limitations concerning the

messageIDrangesassignedtothedierentmodes.

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Function

General

3-2

The following image gives an overview of the provided CAN architecture:

CAN Layer 2

Buffer 28

Buffer 29

Buffer 30

Buffer 31

CAN Basic Services

Queue

high

Priority

CAN

Direct Access

Queue

high

Priority

Queue

low

Priority

Queue

low

Priority

CAN Data Mapping

CAN Process image

Configuration DB

PLC

Periphery

Managment

CAN Bus

ID = high Prio ID = low Prio

Indication

Process image

Timer

Send

ID = any Prio

Buffer 0 - 27

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Function

CAN Direct Access

3-3

3.2 CANDirectAccess

3.2.1 General

TheCANcontrollerprovides32messageobjects.Eachobjectrepresentsonemes-

sagebuerofupto8databytesandisfreelycongurableasreceiveortransmit

buerandmaskable.

The user interface provides access to the hardware controller as direct as possible.

Thereforeallaccessesareorientedtowardsmessageobjectsratherthanjustsimple

messages.EachSystemFunctioncallrequiresasparametertheObjectIDreferring

totherespectivemessageobjectintheCANcontroller.Thisgivestheapplicationfull

access to the functionality of each CAN controller.

Of course not every CAN controller provides exactly the same functionality which is

why a certain level of abstraction is required. Also some specialties of the used CAN

controller must be known to the application programmer. These are explained in the

detailed description hereafter.

3.2.2 Pollingvsinterrupts

Both System Functions for receiving and sending messages provide means to oper-

ate in poll and interrupt mode. Poll and interrupt modes can also be used concur-

rentlyfordierentmessageobjects.Thesameobjectcanalsobepolledtorequestits

status while it is in interrupt mode.

The choice of poll or interrupt mode is entirely up to the application programmer and

mustbechosenaccordingtotheapplication’srequirements.

Note however that it is not question of the hardware interrupts of the CAN controller

here. The described interrupts are an abstraction to the application.

3.2.3 RemotetransmissionrequestsRTR

The driver supports handling of remote transmission requests for both receive and

transmitobjects.

AsendobjectthatisactivatedforRTRwillsendtheframeonlyuponreceptionofa

corresponding RTR from another station.

AreceiveobjectreleasedforRTRwillissueanRTRframeandstoretheresponsein

theobject’sdatabuer.

AmessageobjectisnotconstantlyconguredforRTRframes.Foreachjobitcanbe

used for RTR handling or not.

3.2.4 Initialisationsequence

Before any message transfers can occur the driver must be initialised and started by

executing the following steps:

1) CongurethedriverwiththebasicparametersetusingtherespectiveSystem

Function

2) CongureeachmessageobjectusingtherespectiveSystemFunction

3) ReleaseallreceptionbuersbycallingtherespectiveSystemFunctionfor

 eachreceiveobjecttobereleased

3.2.5 Self-receivedframes

The CAN controller does not receive self-transmitted frames even if there exists a

matchingreceivemessageobject.

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Function

CAN Basic Services

3-4

3.3 CANBasicServices

3.3.1 General

TheimplementationofQueuesprovidestheuserwithaconceptthatisanalogueto

the BasicCAN principle implemented by several CAN controllers. The user gets ac-

cess to one receive and one send queue. In this mode the user does not care about

ordirectlyhandlethemessageobjectsintheCANcontroller.Thistaskisperformed

bytheQueue-Handler.

ThequeuesusethetwomessageobjectswiththehighestnumberintheCANcon-

troller.AccesstothesemessageobjectsisblockedfortheCANDirectAccessSys-

temFunctionsassoonasthequeuesarecongured.

It is possible to operate in CAN Direct Access and CAN Basic Services modes simul-

taneously.Toensureacorrecthandlingofreceivedmessages,theIDrangescong-

uredforeithermodemustbeseparated(i.e.notoverlapping).

All CAN IDs can be received and sent over the same queue. The ID range to be

handledbythequeuesiscongurable.ThisleavesthepossibilityfortheexcludedID

range to be handled with the System Functions in the CAN Direct Access mode at the

sametime.Thequeuedepthiscongurableaswell.

The send queue allows sending more than one telegram at a time without waiting

for the successful transmission. There is no feedback possible for transmission of a

singlemessage.Howeverwhenthequeuebecomesempty(i.e.thelastmessagehas

successfullybeensent)acorrespondinginterruptcallcanbegenerated.

The receive queue avoids the loss of messages on reception. There is no indication

of the reception of a single message. However when a message is received into an

emptyqueue(i.e.therstmessageisreceived)aninterruptcallcanbegenerated.

3.3.2 RemotetransmissionrequestsRTR

Remote requests RTR cannot be handled with-in the queues.

3.3.3 Initialisationsequence

Before any message transfers can occur the driver must be initialised and started by

executing the following steps:

1)CongurethedriverwiththebasicparametersetusingtherespectiveSystem-

Function

2)CongurethereceiveandtransmitqueueusingtherespectiveSystemFunction

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Function

CAN Data Mapping

3-5

3.4 CANDataMapping

3.4.1 General

The CAN Data Mapping provides an intermediary CAN application layer that auto-

maticallymanagesthecopying,transmissionandreceptionofPLCinputandoutput

media.

This principle shows certain similarities with the PDOs in CANopen. However it is

clearlylocatedsomewherebetweentheCANLayer2andtheCANopenapplication

layerandthereforeitisSBC-specic.

The CAN Data Mapping supports the following functionalities:

● ArangeofCANmessageIDscanbeassignedtotheCANDataMappingsuch

 thattheCANdataisdirectlymappedtothePLCinputandoutputmedia

● Both,processimageanddirectperipheryaccessesaresupportedbytheCAN

 DataMapping(xx7)

● ThecongurationofthedatamappingisdenedinaDB/DBX

● TheoutputmediaareautomaticallycopiedtotheconguredCANtelegramsat

 theendofthePLCcycle

● Thetransmissionofalloutputsistriggeredbyacongurablecyclictimer

● Anoptionallowsonlysendingtelegramswhosedatahaschangedsincethe

last transmission

● ThedataofreceivedCANtelegramsisautomaticallycopiedtothecongured

 PLCinputmediaatthebeginningofthePLCcycle.

3.4.2 CANprocessimage

The CAN Data Mapping has its internal process image which represents the periph-

erytothePLC.ThetransferofthisimagetoandfromotherCANnodesisperformed

by the CAN Data Mapping in an autonomous manner.

Thefollowinglimitationsarecurrentlydened:

CANprocessimagesizeinbytes,total(Rx+Tx) 2048

Maximalnumberofmessages,total(Rx+Tx) 256

8 bytes are allocated for each message ID even if not all bytes of that message are

mappedtoPLCmedia.Theavailablememoryspaceisevenlydistributedbetween

inputs(Rx)andoutputs(Tx).

3.4.3 Conguration

CANmessagesrespectivelyIDscanbeconguredtoexchangedatawiththeCAN

processimage.AllIDsmustbeinahighpriorityrangewhichisdenablewithasingle

mask, typically from 0 to a threshold.

One CAN ID is associated to one single telegram per transfer direction. Hence, it is

notpossibletodeneseveraltelegramswiththesameIDfortransmission(outputs)

orreception(inputs).

The length of the transmittedoutputtelegramsisdenedbythehighestbyteinthe

messagetowhichaPLCoutputismapped.Ifbytes0and1arenotmappedwhile

bytes2and3aremappedforaspecicmessageID,then4byteswillbetransmitted

each cycle, where bytes 0 and 1 are always zero.

The length of the receivedinputtelegrams does not necessarily have to correspond

to the number of mapped input bytes. Two cases are of importance:

Saia-Burgess Controls AG

CAN Manual for Saia PCD Classic CPUs │ Document 26-839 ENG05 │ 2019-05-27

Function

CAN Data Mapping

3-6

● Areceivedtelegramcontainsmorebytesthancongured:Allbytescongured

in the DB are copied to the CAN process image. The remaining bytes are igno

red resp. the user cannot access them

● Areceivedtelegramcontainslessbytesthancongured:Allreceivedbytesare

copied. The remaining bytes in the CAN process image are left unchanged.

3.4.4 Datatransfer

Thedataofallreceivedandconguredtelegramsisautomaticallytransferredtothe

internal CAN process image. The outputs are transferred from the CAN process im-

ageandaresentwhentheconguredtimerelapses.Itisimportanttonotethatdur-

ingtransmissionoftheoutputstheCANbusisusedtofull100%ofitscapacity.

TheinputsarecopiedfromtheCANprocessimagetothePLCprocessimageatthe

beginningofthePLCcycle.TheoutputsaretransferredfromthePLCprocessimage

totheCANprocessimageattheendofthePLCcycle.Furthermore,directperiphery

accesses allow accessing the CAN process image at any time.

Since the received data is automatically copied from the CAN message to the pro-

cess image it is not ensured that the user will get the data of every single received

telegram. A following telegram will overwrite the data of the previous telegram with

the same message ID. If the user has not read the data in-between, the data of the

previous telegram will be “lost” to the user.

It is optionally possible to only send telegrams where at least one byte has changed

since the last transmission. However this requires more computing power before

each transmission.

Likewiseithastobekeptinmindthataftereachreceptionthecorrespondingmap-

ping entry must be searched. The time for this search increases with the number of

input mapping entries.

AssoonastheCANDataMappingiscongured,buers28and29oftheCANcon-

troller are reserved. Those are then not accessible anymore for CAN Direct Access or

CAN Basic Services.

IftheCANDataMappingreceivesamessagewhoseIDisnotcongured,thismes-

sage is ignored and data is lost.

3.4.5 RemotetransmissionrequestsRTR

TheuseofRemoterequestsisnotpossiblewith-inthecongurationoftheCANData

Mapping.

3.4.6 Initialisationsequence

BeforetheCANDataMappingcanbecongured,theCANdrivermustbeinitialised

and started. The following steps must be executed:

1) ConguretheCANdriverwiththebasicparametersetusingtherespective

System Function.

2) ConguretheCANDataMappingusingtherespectiveSystemFunction

Page is loading ...

SBC CAN-Functions on Classic PCDs Owner's manual

SBC CAN-Functions on Classic PCDs Owner's manual

SBC CAN-Functions on Classic PCDs Owner's manual

Related papers

Other documents