Technical FAQs

Ask a Question

How to write to the coils of a Quantum PLC using a WRITE_VAR

Goals and Symptoms

How to write to the coils of a Quantum PLC using a WRITE_VAR

Facts and Changes


Causes and Fixes

The following example demonstrates how to use a WRITE_VAR to write to the coils of a Modicon
Qunatum PLC, using an '140NOE771xx' Ethernet module.


Writes coil 000023 through 000026 in a Quantum PLC that is configured for Modbus address 20.

Expression (3.120) instructs the WRITE_VAR to send the command out of XWAY address 3.120.
A value of 100 is added to the Modbus address for defining the XWAY address to a Modbus device.
The XWAY address must also be defined in the 'Connection Configuration' table of the Premium
Ethernet module device port configuration.

Expression 4.0.1 invokes the WRITE_VAR command to send the data out of
'Module 4', 'Channel 0', 'Sender address Ad0=1' in the Premium PLC. For a Modicon
device, the Sender address Ad0 is alsways equal to 1.

Expression '%M',22,4 will write four bits to coil 000023 through coil 0000026 in the Quantum PLC. The
reason for the offset is because Premium starts of with internal bit %M0 and the Quantum starts with
coil 000001.

Expression %MW920:1 is used for the starting word of the 'Transfer Table' with a length of 1 word. The
bit structure is reversed for the transfer table. (i.e., word 920 is represented as 2#0000 0000 0000 1111
in the PL7 animation table for the four bits written in the above instruction.

Expression %MW925:4 is the starting word for the 'Management Word' table with a length of 4 words.

Was this helpful?
What can we do to improve the information ?