Rockwell Automation 1771-TCM,D17716.5.108 TEMPERATURE CONTROL MOD - Manual (Page 26)

Communicating with Your Module
Chapter 3
3-4
TPO Bits
The loop designations of the heat/cool (control-variable) TPO bits in the
high byte of the input image word are as follows.
7 6 5 4 3 2 1 0
Loop 1
Loop 2
Loop 3
High byte of input image word (heat/cool
TPO bits for control variable)
Loop 4
Loop 5
Loop 6
Loop 8
Loop 7
Controlling Heating Elements Only
In applications where the control variable TPO of each loop is used for
only heating, the ladder logic for data single-transferred to/from the
1771-TCM module must do the following:
Write the decimal value 35 (binary 00100011) to the high
byte of the output image word of the 1771ĆTCM module.
Read the low byte of the input image word of the
1771ĆTCM module.
If the low byte of the input image word of the 1771ĆTCM
module has the value 35
10
, move the value from the high
byte of the input image word of the 1771ĆTCM module to
the output image byte of the output module driving the
heating elements.
If bit 0 (watchdog timer) of the low byte of the input
image word of the 1771ĆTCM module off, zero the output
image byte of the output module driving the heating
elements.
If bit 0 (watchdog timer) of the low byte of the input
image word of the 1771ĆTCM module on and the low
byte of the input image word of the 1771ĆTCM module
does not have the value 35
10
, do not write to the output
image byte of the outputs driving the heating elements.
High byte of 1771ĆTCM
output word
Low byte of 1771ĆTCM
input word
High byte of 1771ĆTCM
input word
HeatingĆelement outputs
HeatingĆelement outputs
35
10
?
35
10
00000000
2