TE Technology TC-36-25-RS485 - Manual (Page 44)

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II. Examples:
A) Set the controller to control via a computer programmable set point.
1. The controller address, AA, is in this example 62
16
. (The default address of the controller is 98
10
, but this
must first be converted to hexadecimal for the proper send value.)
2. The write command, CC, for “SET TYPE DEFINE” is 29.
3. A data value of “0” selects a computer communicated set value, so the eight‐character send value
DDDDDDDD is 00000000.
4. Compute the checksum (SS) by adding the hexadecimal ASCII values of the following characters: 6, 2, 2,
9, 0, 0, 0, 0, 0, 0, 0, and 0:
ASCII Character:
Hexadecimal Value:
6 36
2 32
2 32
9 39
0 30
0 30
0 30
0 30
0 30
0 30
0 30
0 30
Sum 0253
16
The 8‐bit checksum is the 8 least significant binary bits of the sum, represented as 53 in hexadecimal.
5. Combining all of these characters into one string we send: (stx)62290000000053(etx).
6. If the temperature controller receives the command and the checksum is correct, it will send back:
(stx)0000000080(ack). If the checksum is not correct the temperature controller will send back:
(stx)XXXXXXXXc0(ack).
B) Send the set temperature of 10.00 to the controller.
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
(10.00 x 100 = 1000).
4. Convert 1000
10
to hexadecimal (3e8
16
) and add on leading zeros to make the eight‐character send value
DDDDDDDD (000003e8).
5. Compute the checksum (SS) by adding the ASCII values of the following characters: 6, 2, 1, c, 0, 0, 0, 0,
0, 3, e, and 8:
ASCII Character: Hexadecimal Value:
6 36
2 32
1 31
c 63
0 30
0 30
0 30
0 30
0 30
3 33
e 65
8 38
Sum 02bc
16
The 8‐bit checksum is the 8 least significant binary bits of the sum, represented as bc in hexadecimal.
6. Combining all of these characters in one string we send: (stx)621c000003e8bc(etx).