User`s guide

Page 59

Controlinc 1746-C (Version 5.21) Network Master Users Guide (2004-11-18)

5.4.5. Table [5]: Valve Position Setpoint … 0 – 4095

Words [4  63] PLC access: Read / Write

This table commands the actuators to move to a setpoint position designated by the PLC. When the

1746-C sends the new value to the actuators (telling them to move), it uses the Modbus function 6

command to write to holding register [11] in the actuator.

By sending a numeric value from 0

 4095, the actuator will be commanded to move to a position

based on:

• 0 (0x0000) = 0% Open (closed)

• 4095 (0x0FFF) = 100% Open

A read back of Table [5] will

• If a write command issued: reflect the write command accepted by the 1746-C

• If a read command issued: reflect the current value of the setpoint register in the actuators.

Notes:

• Only values 0



4095 are allowed to be written by the PLC … all others are ignored.

• Any EIM actuator may use position control via setpoint values. For the tightest position

possible with minimal overshoot or undershoot, the actuator must have the solid-state or VFD

control option. Please read the Controlinc Quick Startup Guide for more information.

• If the actuator position has been moved while the PLC is down or the valve was moved while in

local control, then as soon as the PLC and actuators are communicating and accepting remote

commands, it will move according to the existing value in this Table.

• Issuing a command in Table [5] will “zero out” any discrete (block) mode command issued on

Table [3] for the particular valve.

• Any NEW discrete control command in table [3] will change the corresponding setpoint control

value in Table [5] to either 0 / 4095 / or “current position”

• If the 1746-C ever returns a value of 0xFFFF for a setpoint indication in this table, it means that

the particular actuator is returning the standard “invalid setpoin

t” and is currently stopped and

waiting for a new command to move the valve.