TE Technology TC-36-25-RS232 - Manual (Page 45)

The 8-bit checksum is the 8 least significant binary bits of the sum, represented as ef in
hexadecimal.
6. Combining all of these characters in one string we send: (stx)001cffffff6aef(etx).
7. If the temperature controller receives the command and the checksum is correct, it will send back:
(stx)ffffff6afb(ack). If the checksum is not correct the temperature controller will send back:
(stx)XXXXXXXXc0(ack).
D) Read the actual temperature of the control thermistor (INPUT1) from the controller at address 00.
1. Let us assume the actual temperature is 2.50 °C, and the working units have been defined as °C.
This means that the controller will return a value in °C.
2. The controller address, AA, is by definition 00.
3. The control command, CC, for “INPUT1” is 01.
4. There is no send value, so we can just calculate the checksum (SS) by adding the ASCII values of the
following characters: 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0:
ASCII Character: Hexadecimal Value:
0 30
0 30
0 30
1 31
0 30
0 30
0 30
0 30
0 30
0 30
0 30
0 30
Sum 0241
16
The 8-bit checksum is the 8 least significant binary bits of the sum, represented as 41 in hex.
5. Combining all of these characters in one string we send: (stx)00010000000041(etx).
6. If the temperature controller receives the command and the checksum is correct, it will send back:
(stx)000000fae7(ack). The e7 at the end of the string is the checksum of “000000fa”. The value
000000fa
16
converts to 250
10
. This number must then be divided by 100
10
, so the value would be
interpreted as 2.50 °C. As in the other examples, if the checksum from the query were not correct
the temperature controller would send back: (stx)XXXXXXXXc0(ack).
III. RS232 Communications Parameters (JP4 connector on controller board)
A. Baud Rate 9600
B. No Parity
C. 1 Start Bit 1 Stop Bit
NOTE if you are using communications software different from the one supplied with the controller: The
demands of temperature control require a relatively large portion of the processing power of the onboard
microcontroller. It is possible for a host computer to send data too quickly for the controller to receive and
update. TE Technology recommends adding a delay between each character sent to allow the controller sufficient
time to process the information. One millisecond might be a good delay time to use initially, but the exact time
will vary depending on the host computer’s hardware and the particular demands on the controller at the
moment.
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