Simatic 505 SoftShop
9 - PID Loops
••••
153
Bit
PID Loop Function
1 0 Loop is in auto mode
0 1 Loop is in cascade mode
6
1=Error is positive
1=Error is negative
7
1=Process Variable is in high high Alarm
8
1=Process Variable is in high Alarm
9
1=Process Variable is in low Alarm
10
1=Process Variable is in low low Alarm
11
1=Process Variable is in yellow deviation alarm
12
1=Process Variable is in orange deviation alarm
13
1=Process Variable is in rate of change Alarm
14
1=Broken transmitter alarm
15
1=PID Loop is overrunning
16
1=Unused
Sample Rate
Enter a time in seconds in the SAMPLE RATE field.
The sample rate determines how often deviation Alarm bits and
associated math are evaluated. Sample rates are programmable in 0.1
second increments, with Alarms checked at least once every two seconds.
The sample rate can be any floating point number between 0.1 and
1.6772 x 10
6
seconds.
Process Variable Address
Enter an address: V, WX, WY, or select
NONE
in the PROCESS
VARIABLE ADDRESS field.
A process variable must be specified for each PID Loop. The process
variable can be taken from the following:
•
A word input or output module - The programming table uses a
WX or WY address.
•
A location in V-Memory - Uses an address in V-Memory in the
programming table. When a special calculation is performed on
a process variable, the result is stored in V-Memory where the
Loop accesses it.
If you select
NONE
, the PID Loop does not read an address to obtain the
Process Variable.
Low Process Variable Range
Enter the low value of the process variable in the Process Variable Range
Field.
You must specify the engineering values that correspond to the lower
range of the input span.
High Process Variable Range
Enter the high value of the process variable in the Process Variable
Range Field.