Reading Control Data - Honeywell UDC3500 Product Manual

Analog Parameters
• Whenever analog register addresses xx01 through xx7F (those that can be
changed via communications) are changed, a Write cycle occurs after receipt of
the message and the response is returned.
Override Parameters
• Override analog register address xx7D (computer setpoint) is not stored in non-
volatile memory. It can be changed as frequently as desired with no effect on non-
volatile memory retentivity, but the controller must remain in the slave mode.
Digital Parameters
• Whenever digital configuration register addresses xx80 through xxFF are updated
via communications, the non-volatile memory is updated as soon as the message
is received.
Communications Transfer Rates
• Reads minimum 20 milliseconds and writes minimum 200 milliseconds.
Supported Function Codes
• IR port 20 and 21
• RS485 and Ethernet ports 1,2,3,4,6,8,16,17,20,21
Communications Modes of Operation
• When the Shed Timer is enabled and a write or override occurs the controller will
enter Slave Mode. The keypad is locked from the operator. The purpose of this
mode is that if communications is lost and the shed timer times out then the
controller will enter a known state of operation. The configuration of the "Shed
Mode and Output" and Shed Setpoint Recall are used to configure the controller's
shed state. While in Slave Mode pushing the
mode. The local operator then has control of the output. The controller is in
Monitor Mode if the Shed timer is disabled.

10.2 Reading Control Data

Overview
The following control data can be read from this instrument:
• Input 1
• Input 2
• Input 3
• Input 4
• Input 5
• PV, SP, Output for each Loop
10/05
Modbus Read, Write and Override Parameters plus Exception Codes
UDC3500 Universal Digital Controller Product Manual
Man Man Man
key enters Emergency Manual
Auto Auto Auto
329