Honeywell UDC3500 User Manual

Modbus Read, Write and Override Parameters plus Exception Codes
3/07 UDC3500 Universal Digital Controller Product Manual 355
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.
Table 10-7 Computer Setpoint Selection
Parameter Register
Address
Data
Type
Access Data Range or
Enumerated Selection
Description ID Hex Decimal
Computer
Setpoint
Loop1
125 007D 125 FP R/W Value from computer with
Ratio and Bias applied by the
controller. Within the PV
Range Limits in Engineering
Units or Percent.
Computer
Setpoint
Loop2
125 017D 381 FP R/W Value from computer with
Ratio and Bias applied by the
controller. Within the PV
Range Limits in Engineering
Units or Percent.
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.

Honeywell UDC3500 Specifications

General

Brand	Honeywell
Model	UDC3500
Category	Controller
Language	English