Cole Parmer POLYSTAT User Manual

2
Appendix
Cole Palmer
Checksum region
Lead char Addr-MSB Addr-LSB Command n d-bytes d-byte 1 ... d-byte n Checksum
CA or CC 0 1
Lead char 0xCA (RS-232) 0xCC (RS-485)
Device address is 1 (RS-232)
Addr-msb Most significant byte of device address (RS-232: 0).
Addr-lsb Least significant byte of device address is 1 (RS-232).
Command Command byte (see Table 1).
n d-bytes Number of data bytes to follow (00 to 03 hex).
d-byte 1 1
st
data byte (the qualifier byte is considered a data byte).
... ...
d-byte n n
th
data byte.
Checksum Bitwise inversion of the 1 byte sum of bytes beginning with the most
significant address byte and ending with the byte preceding the checksum.
(To perform a bitwise inversion, "exclusive OR" the one byte sum with FF hex.)
CA 00 01 20 00 DE
command byte
0 bytes of data
The checksum is the bitwise
inversion of 21
(00+01+20+00)
byte values are in hex
NOTE All byte values are shown in hex, hex represents the binary values that must be sent to the chiller.
Do not use ASCII. 
The framing of the communications packet in both directions is:
The master requests information by sending one of the Read Functions as shown in Table 1. Since
no data is sent to the chiller during a read request, the master uses 00 for the number of data bytes
following the command byte.
The chiller will respond to a Read Function by echoing the lead character, address, and command byte,
followed by the requested data and checksum. When the chiller sends data, a qualier byte is sent rst,
followed by a two byte signed integer (16 bit, MSB sent rst). The qualier byte indicates the precision
and units of measure for the requested data as detailed in Table 2.
As an RS-232 example, the master requests to read internal temperature unit address 01 by sending:
CA 00 01 20 03 01 FF F4 E7
command byte
3 bytes to follow
The qualifier byte of 01 indicates a precision of 0
decimal point and units of °C. The temperature of
-12°C is -12 decimal = FFF4 hex.
If the temperature is -12°C, the unit would reply:
The checksum is the bitwise inversion of 18
(00+01+20+03+01+FF+F4) = 218
Take the LSB = 18
Bitwise inversion = E7

Cole Parmer POLYSTAT Specifications

General

Brand	Cole Parmer
Model	POLYSTAT
Category	Laboratory Equipment
Language	English