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Thermo Scientific D-4 ThermoFlex Appendix D Thermo Scientific Thermo Scientific Analog V alues Qualifier Byte b.7 b.6 b.5 b.4 b.3 b.2 b.1 b.0 A qualier byte of 0x12 indicated that the value contains one decimal point and th…
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Appendix D
ThermoFlex D-3
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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:
Checksum region
Lead char Addr-MSB Addr-LSB Command n d-bytes d-byte 1 ... d-byte n Checksum
Lead char 0xCA (RS-232) 0xCC (RS-485)
Device address is 1 (RS-232)
Addr-msb Most signicant byte of slave address (RS-232: 0)
Addr-lsb Least signicant byte of slave address (RS-232: 1)
Command Command byte (see Table of Commands)
n d-bytes Number of data bytes to follow
d-byte 1 1
st
data byte (the qualier 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
signicant address byte and ending with the byte preceding the checksum.
(To perform a bitwise inversion, "exclusive OR" the one byte sum with FF
hex.)
When a command has no value associated with it (e.g., REQ ACK), “n d-bytes” will be set to 0.
Values such as temperature and ow are sent as either 2 or 4 byte signed integers, depending on
how they are stored in the controller RAM.
When the controller sends a value, a qualier byte is sent rst, followed by a 2 or 4 byte
integer (the least signicant byte is sent last). The qualier indicates the precision and units of
the value. The host does not send the qualier byte; it must send the value using the correct
precision, units and number of bytes. The host rst inquires about a value it wants to change,
then uses the number of data bytes and the qualier byte it receives to generate the proper
integer to send.
OxCA/OxCC
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D-4 ThermoFlex
Appendix D
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Thermo Scientific
Analog Values
Qualifier Byte
b.7
b.6
b.5
b.4
b.3
b.2
b.1
b.0
A qualier byte of 0x12 indicated that the value contains one decimal point and the units
are °F , e.g., 98.6°F.
Example to set setpoint to 25°C:
If the temperature units are unknown, before changing the setpoint send a command to request
setpoint. The response will include both the precision and units. Precision is xed at 0.1 and units can
be either °C or °F. If the units are already known skip to step 3.
1. Master sends: CA 00 01 70 00 8E (REQ SETPOINT1)
2. Slave responds: CA 00 01 70 03 11 00 C8 B2 Precision =0.1, units =°C, value=200
(200 x 0.1°C=20.0°C)
Response indicates:
uses a 2 byte integer (nn=03)
precision and units are 0.1°C (d1=11)
3. Master sends: CA 00 01 F0 02 00 FA 12 (Set Setpoint 1 to 25.0°C)
4. Slave responds: CA 00 01 F0 03 11 00 FA 00 Precision =0.1, units =°C, value=250
(250 x 0.1°=25.0.0°C)
See Additional Command Examples in this Appendix.
Unit of Measure
Index Unit
0 NONE
1 Temperature in °C
2 Temperature in °F
3 Flow liters per minute
4 Flow in gallons per minute
5 Time in seconds
6 Pressure in PSI
7 Pressure in bars
8 Resistivity in MΩ-cm
9 %
10 Volts
11 Pressure in kPa
Precision of measurement
Unit of measure index
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Appendix D
ThermoFlex D-5
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Table of Commands
Command M: Master Sends Notes
S: Slave Responds
Request Status
REQ ACK M: lc a1 a2 00 00 cs protocol version v1=0; v2=1
S: lc a1 a2 00 02 v1 v2 cs
REQ CONTROLLER SW VER M: lc a1 a2 02 00 cs Controller SW version in ASCII
or FIRMWARE CHECKSUM S: lc a1 a2 02 nn d1 … dn cs
Example: Request SW version, controller returns 084992.2N
1. Master sends: lc a1 a2 02 00 cs
2. Slave responds: lc a1 a2 02 0A 30 38 34 39 39 32 2E 32 4E 20 E4
Example: Request controller checksum, controller returns 20FA
1. Master sends: CA 00 01 02 01 01 FA
2. Slave responds: CA 00 01 02 04 32 30 46 41 0F
REQ DISPLAY MSG M: lc a1 a2 07 00 cs Display message in ASCII
S: lc a1 a2 07 nn d1 … dn cs
REQ STATUS M: lc a1 a2 09 00 cs see Request Status Table in this Appendix
S: lc a1 a2 09 nn d1 … dn cs
ERROR M: Response Only!
S: lc a1 a2 0F 02 en ed cs ed = Error Data en = Error Number
1: Bad Command
2: Bad Data
3: Bad Checksum
See Error in this Appendix