Using A Computer Setpoint (Overriding Controller Setpoint); Table 10-7 Computer Setpoint Selection - Honeywell UDC3500 Product Manual

10.6 Using a Computer Setpoint (Overriding Controller Setpoint)

Overview
You can use a setpoint generated from the computer to override the setpoint being used
by the controller. The value generated by the computer will have ratio and bias applied
by the controller.
Register Addresses
Use the identifying code in Table 10-7 to enter the computer setpoint.
Parameter
Description ID
Computer 125
Setpoint
Loop1
Computer 125
Setpoint
Loop2
Shed
The computer setpoint override will continue until SHED from communications occurs
or the controller is placed into monitor mode through communications. Doing periodic
SLAVE READS within the shed time will allow the override to continue until
communication is stopped and shed time elapses. Does not apply to IR communications.
ATTENTION
0 Shed (code 79) allows the override to continue indefinitely or until the reset shed timer
register address 1B90 and 1B91 is written using function code 6 or parameter ID 127
using function code 21. Any data value can be written because it is ignored.
When SP is overridden, the upper display becomes "C" momentarily, and the lower
display shows the CSP value as CSP XXXX.
3/07
Modbus Read, Write and Override Parameters plus Exception Codes

Table 10-7 Computer Setpoint Selection

Register
Address
Hex Decimal
007D 125 FP
017D 381 FP
UDC3500 Universal Digital Controller Product Manual
Data Access
Type
R/W Value from computer with
Ratio and Bias applied by the
controller. Within the PV
Range Limits in Engineering
Units or Percent.
R/W Value from computer with
Ratio and Bias applied by the
controller. Within the PV
Range Limits in Engineering
Units or Percent.
Data Range or
Enumerated Selection
355