Rockwell Automation 1771-PD PID MODULE (+DU) - Manual (Page 130)

Programming
Chapter 3
3Ć87
Figure 3.32
Decouple Control
Process
PID
SP2 E
PV2
BIAS2
V
FF
11137
SP1 E
BIAS1
V
PV1
PID
PC Processor Interactive Control
The PID module is a self-contained 2-loop process controller. Because
the PC processor can program and monitor the PID module, there are
numerous types of interactive control which can be performed. The
following describes a few interactive control schemes.
If a process variable signal is required other than +4 to +20mA or +1 to
+5VDC, another input module could be used to read the process variable.
The PC processor could transfer this value to the PID module. For
example, the PC processor could read a thermocouple input through the
Thermocouple Input Module (cat.no. 1771-IX) and write the input value
to the PID module.
The PC processor could also read digital inputs from transmitters with
BCD output and transfer the information to the PID module. Block
transfer timing must be considered.