Remote I/O expansion
Question
Although I can add up to two expansion I/Os, there still isn’t enough input/output.
Can I add more?
Answer
Consider a remote I/O system using Modbus/RTU using the RS-485 port.
As the number of expansion cards increases, the refresh rate of remote I/O will decrease.
Please download the sample program below.
(If you set the port to be used as Ethernet, expansion via Ethernet is also possible.)
Sample programm
Example of keeping input/output status during communication error
Download here
-Master-
Set the station number of Port3 to #1.
Write outputs Y301-Y316 of the master station to outputs Y001-Y016 of the slave station using the Send command.
Conversely, read inputs X001-X016 of the slave station to internal relays C21-C36 of the master station using the Receive command.
-Slave-
Set the station number of Port3 to #2.
Only END command.
Example of setting all input/output status to off when there is a communication error
Download here
-Master-
Flicker Y316 for 500mS.
If the execution result of the Receive command is an error, internal relays C21-C36 are all turned off.
-Slave-
Monitor Y016 and if it does not change for a certain period of time (600mS), turn off all Y1-Y8.
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