Addressing Reference
1785 PLC-5
22
Table P
Example PID Control Addresses
To Address:
PLC Data Type:
Example Address:
Whole PD Control Structure
structure
$PD13:0
Set-point value
IEEE float
$PD13:0.SP
Proportional-gain value
IEEE float
$PD13:0.KP
PID-initialized bit
bit
$PD13:0.INI
SP out-of-range bit
bit
$PD13:0.SPOR
Table Q
PID Control Block in Integer File
Word:
Contains:
Term:
Range:
0
Bit 15
Enabled (EN)
Bit 13
Done (DN)
Bit 11
Set point out of range
Bit 10
Output alarm, lower limit
Bit 9
Output alarm, upper limit
Bit 8
DB, set when error is in DB
Bit 7
Resume last state (0 = yes, 1 = hold last state)
Bit 6
Derivative action (0 = PV, 1 = error)
Bit 5
Setpoint descaling (0 = no, 1 = yes)
Bit 4
Set output (0 = no, 1 = yes)
Bit 3
Output limiting ((0 = no, 1 = yes)
Bit 2
Control (0 = direct, 1 = reverse)
Bit 1
Mode (0 = automatic, 1 = manual)
Bit 0
Equation (0 = independent, 1 = ISA)
1
reserved
2
Setpoint
SP
0 thru 4095 (unscaled)
S
min
thru S
max
(scaled)
3
Independent:
Proportional gain (unitless)
K
P
0 thru 327.67
3
ISA:
Controller gain (unitless)
K
C
0 thru 327.67
4
Independent:
Integral gain (1/s)
K
I
0 thru 327.67
ISA:
Reset term (minutes per repeat)
T
I
0 thru 327.67
5
Independent:
Derivative gain
K
D
0 thru 327.67
ISA:
Rate term x 100 (minutes)
T
D
0 thru 327.67
6
Feedforward or bias
FF/Bias
0 thru 4095
7
Maximum scaling
S
max
–32,768 thru +32,767
8
Minimum scaling
S
min
–32,768 thru +32,767
9
Dead band
DB
0 thru 4095 (unscaled)
S
min
thru S
max
(scaled)
10
Set output
SETOUT
0 thru 100%
11
Maximum output limit (% of output)
L
max
0 thru 100%
12
Minimum output limit (% of output)
L
min
0 thru 100%
13
Loop update time (seconds)
dt
0.01 thru 327.67