Writing to Modbus from FX30

Hello everyone,

I am trying to write to an IO board using modbus, and I am having trouble writing to a digital output. The modbus address for these inputs are 00001-00006, and I can read them using Coil as the starting address as shown below.

In the Modbus guide ( Modbus Guides (octave.dev)) it is clear how to write to a Holding Register (HLD) as shown below.

Here, to write to the analog output, I use the HLD as the starting address and the “address” field acts as the offset. I think I could write to the digital output if I knew the three letter code, and I think this is it shown below.

According to this page on the documentation, DO should be the code used as the the “type”. Modbus Reference (octave.dev)

Wilson Teachey

Hi Wilson,

Your question is not very clear, but I confirm you that “DO” is the correct type for Coils (also known as Digital Output).

Let me known of you need any further information.

Hello Guillaume,

Sorry the question was not clear. The “DO” code was the primary question that I had. I got it working this morning, but I’m not sure what changed to make it work.

Wilson Teachey