2. Baldwin Boxall
  3. BVR485R

Baldwin Boxall BVR485R Operating instructions

  • Hello, I'm ready to assist you with information about the BVR485R Repeater/isolator module. This document provides operating instructions, explaining how the module extends RS485 communication distances, provides galvanic isolation, and supports ring topology. I've reviewed its contents and can help with your questions about its setup, features, and troubleshooting.
  • What is the typical distance limit for an RS485 multi-drop data link without the BVR485R?
    What type of power supply is required for the BVR485R?
    What is the purpose of the LEDs on the BVR485R?
Baldwin Boxall Communications Ltd.
Wealden Industrial Estate, Farningham Road
Crowborough, East Sussex, TN6 2JR
Telephone: 01892 664422
Fax: 01892 663146
Website: www.baldwinboxall.co.uk
Email: mail@baldwinboxall.co.uk
IBVRS485R
Issue 1 02/05/02
BVR485R
Operating Instructions
- 2 -
Issue 1
BVR485R
RS485 Repeater/isolator module.
Typically a RS485 multi drop data communications link is limited to 1.2Km at 9600 baud
using fire rated cable.
Using the BVR485R can extend the overall distance, provide galvanically isolated ports
preventing earth potential problems and allow for ring topology to be employed.
The BVR485R is housed in a plastic DIN rail mounted module with screw terminations to
accept installation cables on the front side P3 and P4. The local equipment is connected to
P1 and P2 including the 24V DC power required as follows.
A battery maintained 24V must be connected with its 0V to the 2 appropriate terminals on
P2, the current requirement is 20mA.
The local BVR20 or BVCOM RS485 serial port is connected + to A on P1, – to B on P1 and if
the cable includes a screen connect to SC on P1.
Please note that connections A and B on P1 are in parallel with A and B on P3.
The RS485 incoming line is connected to P3 and it is important to ensure that A and B are
not reversed.
The outgoing line is connected to P4 the electrically isolated port, again observe polarity.
When P3 is sending LED 1 will illuminate and when P4 is sending LED 2 will illuminate aiding
fault finding.
The 24V The DC input is converted to 5V using a switch mode techniques providing power
for the line drivers etc.
As the system is half duplex the essential data direction switching is optimised for 9600 baud
and data received at P3 is recovered and sent to the isolated port on P4.
Likewise data received on P4 is sent to the non-isolated port at P3.
In some installation where cable length is long it may be necessary to terminate the line with
a 120 Ohm resistor across A and B of P3.
When the data link is wired as a ring a single break anywhere will not prevent communication
and therefore ring configurations are recommended.
- 3 -
Issue 1
RS485+1
RS485-1
RS485+2
RS485-2
BVRCPU
SLOT 21
120R
RS485+1
RS485-1
RS485+2
RS485-2
BVRCPU
SLOT 21
120R
RS485+1
RS485-1
RS485+2
RS485-2
BVRCPU
SLOT 21
120R
+24V
0V
+24V
0V
+24V
0V
NOTE. Only three RS485 units shown, repeat wiring for full system
Data must wire in and out of 485 isolator as shown.
Data should be wired as a complete ring as shown.
BV20
MICRODRIVE
BV20
MICRODRIVE
BV20
MICRODRIVE
/