FRICK
QUANTUMâ„¢ COMPRESSOR CONTROL PANEL S90-010 CS
COMMUNICATIONS SETUP Page 15
Quantumâ„¢ $ Protocol Specifications
Quantumâ„¢ ($) protocol commands have been added
specifically for the Quantumâ„¢. Unless otherwise shown, 9
characters are returned from the Quantumâ„¢ for a data
value. The data value includes two decimal fields and the
first character position is either; - if the value is negative,
or it is + if the value is positive. For example, if the data’s
value is 25.5; then the value +00002550 is sent. All
temperatures are in degree C and all pressures are in
PSIA. A mode such as Slide Valve mode is returned as an
integer value that represents the mode that it is in. For
example, a +00000000 is sent if it is in manual, or a
+00000100 is sent if it is in automatic, or a +00000200 is
sent if it is in remote. The value zero +00000000 is used to
represent an OFF status and a DISABLED option. The
value one +00000100, which is received as a 1, is used to
represent an ON status and an ENABLED option.
Setpoints are only changed if the value sent is within the
acceptable range. Reference the Frick® Quantum™
Control Panel Maintenance publication S90-010 M for the
setpoints default settings and ranges. The checksum is
the 2 byte hexadecimal sum of each character within the
command or returned answer excluding the command
type identifier, $. If the command’s checksum is replaced
with ??, the Quantumâ„¢ returns a response without using
checksum error checking on the received command (refer
to the Data Packet section for more information). If the
Quantumâ„¢ detects a checksum error, a N (Not
Acknowledged), the Compressor ID code, 02, Carriage
return, and Linefeed are returned.
This document will demonstrate how to communicate to the
Quantumâ„¢ panel using the tables that appear on the
following pages.
Data Packet
If you were interested in viewing the information that is
displayed on the Operating Status - Page 1 screen
(Home screen), you would want to refer to the table
entitled RETURN OPERATING STATUS Page 1 data:
$01D1 table on the next page.
The quickest and easiest way to demonstrate this protocol
is through Hyperterminal (see the section entitled
Hyperterminal later in this manual). After setting up
Hyperterminal and ensuring that all wiring and jumper
configurations are correct, type a $ symbol. This is the
character that will alert all of the Quantumâ„¢ panels on the
communications line that data is on its way. Following the $
symbol, type the ID code of the Quantumâ„¢ that you wish
to query (for instance 01 for the first Quantumâ„¢). After the
ID number, type a D1. The protocol code in the Quantumâ„¢
recognizes this portion of the data packet as a request for
the data that is displayed on the Operating Status - Page
1 screen.
Up to now you have typed the following information:
$01D1. The next thing that must be done is to enter a
checksum value. You may elect to type in a ?? as a
wildcard if you do not have the time to figure the correct
checksum, however, the information that is returned may or
may not always be reliable. The checksum will ensure
reliability.
To arrive at the checksum value for the command you have
just typed, you will need to convert each ASCII digit into
hexadecimal (do not include the $ symbol). For this
example, you will need to take the first digit 0, and referring
to the Conversion Chart at the end of this section, look
down the ASCII column until you find 0. You will notice that
the Hexadecimal equivalent for ASCII 0 is 30 hex. Repeat
the process of looking up each digit in the ASCII column,
and finding its equivalent in the Hexadecimal column, and
write each value down. When all four digits (01D1) have
been converted to hexadecimal, you will need to add the
four values together. Remember, the values are in
hexadecimal format, not decimal. If you are not familiar
with hexadecimal math, you may wish to utilize the
calculator that comes with Microsoft Windows. Look at the
following chart:
ASCII Value of
Data Packaet Hexadecimal
Equivalent
030
131
D44
131
Hex Total = D6
The answer that is arrived at from the previous chart is D6.
This will become the checksum for the data packet, and is
appended to the end of the data that has so far been typed
in.
NOTE: For any calculation that results in an answer of
more than two digits, use only the right most two digits, and
disregard all digits to the left.
The result should look like this:
$01D1D6
Press the [Enter] key. You should see an immediate
response. The format of this response should resemble
something (but not necessarily exactly) like:
A01+00006166+00008618+00008272+00002974+000154
15+00005314+00008501+00000000+00000000+0000000
0+00000341+00000231-00027249B6
Referring to the RETURN OPERATING STATUS Page 1
data: $01D1 table on the next page, we find that the first
line of the response, A01, indicates that an
Acknowledgement (A) was received from device 01 (01).
This is followed by +00006166 (Suction Pressure). The
plus (+) symbol indicates a positive value, followed by
00006166. Since there are two decimal positions assumed,
0006166 equals 61.66 PSIA. Using the +/- symbols as a
delimiter in the above example, each section of 8 digits can
be interpreted by comparing it with the Operating Status
table. The B6 value at the very end of the response is the
checksum value that the Quantumâ„¢ returned, not actual
data.