RS232 Serial Communications (Optional)
This option allows you to remotely control the Chiller and/or output temperature readings to an external
recorder or other auxiliary device. The maximum communications distance for Chillers equipped with the
RS232 option is 15 meters (50 feet).
Serial Connector — A 9-pin D-connector is provided on the back panel of the Chiller for RS232 data
communication. A serial cable that uses only the following pins should be used to connect the Chiller to the
computer:
Pin #2 — data read (data from computer)
Pin #3 — data transmit (data to computer)
Pin #5 — Signal ground
RS232 Protocol — The Controller uses the following RS232 protocol:
Data bits — 8
Parity — None
Stop bits — 1
Flow control — None
Baud rate — Selectable (Chiller and PC baud rates must match).
Communications Commands — Commands must be entered in the exact format shown. Do not send a [LF]
(line feed) after the [CR] (carriage return). Be sure to follow character case exactly. A response followed by
an exclamation point (!) indicates that a command was executed correctly. A question mark (?) indicates that
the Chiller could not execute the command (either because it was in an improper format or the values were
outside the allowable range). A response must be received from the Chiller before another command can be
sent. All responses are terminated with a single [CR].
Command Description Command Format Values Return Message
Set Command Echo SEi[CR]
Echo: i = 1
No Echo: i = 0
![CR]
Set On / Off SOi[CR]
i = 1 to turn on
i = 0 to turn off
![CR]
Set Set Point SSxxx[CR] x = ASCII digit ![CR]
Read Set Point Temperature RS[CR]
+xx.x[CR] or
-xx.x[CR]
Read Temperature RT[CR]
+xx.x[CR] or
-xx.x[CR]]
Read Temperature Units RU[CR] C or F
C[CR] or F[CR]
Read Status RW[CR]
1 = Run
0 = Standby
1[CR] or 0[CR]
Read Compressor Discharge Temperature (°C) RUT[CR]
xxx.x[CR]
Read fault status
RF[CR]
00 = System OK
Faults
![CR]
Read Evaporator Inlet Temperature (°C) REI[CR] xxx.x[CR]
Read Evaporator outlet temperature (°C) REO[CR] xxx.x[CR]
Output continuous data stream, one set per second
Set on/off
RDi[CR]
i = 1 to turn on
i = 0 to turn off
![CR]
RD command results in a continuous data stream. Headers are:
Min.sec, software version, temperature units, temperature setpoint, fluid temperature, remote probe
temperature, not used, compressor discharge temperature, evaporator inlet temperature, evaporator outlet
temperature, heat %, cool %, fan %. Temperatures are always in degrees Celsius.
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110-445
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