TE Technology TC-36-25-RS485 - Manual (Page 45)

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7. If the temperature controller receives the command and the checksum is correct, it will send back:
(stx)000003e8c0(ack). If the checksum is not correct the temperature controller will send back:
(stx)XXXXXXXXc0(ack).
C) Send the set temperature of ‐1.50 °C.
1. The controller address, AA, is in this example 62
16
.
2. The control command, CC, for “FIXED DESIRED CONTROL SETTING” is 1c.
3. Multiply the desired set‐point temperature by 100
10
(‐1.50 x 100 = ‐150).
4. Convert ‐150
10
to hexadecimal by taking the two’s complement of the number. (This can be easily done
by using the formula 2
n
– N, where n is the word‐bit size and N is the absolute value of the number
being converted.) Hence, you have 2 32 ‐ 150 = 429496714610. This value then converts to ffffff6a
16
.
5. Compute the checksum (SS) by adding the hexadecimal ASCII values of the following characters: 6, 2, 1,
c, f, f, f, f, f, f, 6, and a:
ASCII Character: Hexadecimal Value:
6 36
2 32
1 31
c 63
f 66
f 66
f 66
f 66
f 66
f 66
6 36
a 61
Sum 3f7
16
The 8‐bit checksum is the 8 least significant binary bits of the sum, represented as f7 in hexadecimal.
6. Combining all of these characters in one string we send: (stx)621cffffff6af7(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 62
16
.
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 in this example 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: 6, 2,0,1,0,0,0,0,0,0,0,0:
ASCII Character: Hexadecimal Value:
6 36
2 32
0 30
1 31
0 30
0 30
0 30
0 30
0 30
0 30
0 30
0 30
Sum 0249
16
The 8‐bit checksum is the 8 least significant binary bits of the sum, represented as 49 in hex.
5. Combining all of these characters in one string we send: (stx)62010000000049(etx).