NI Modbus Library: Writing subregisters

[mpadlo]

Hello,

I need to write subregister to put IGUS DryveD1 into velocity mode properly.

I'm using NI Modbus Library and I don't know how to write Feed which is in register 6092h:01h.

Is it possible to write register 6092 with subindex 01 with this library?

Block that i use

Registers i want to write

Code snippet

[cordm]

I don't think that's possible, the NI Modbus library certainly can't write a single byte and as far as I know Modbus doesn't work that way.

Instead, read register 6092h, modify the first byte to your liking and write it back. If that doesn't work modify the second byte 😉

[raphschru]

Depending on what Modbus functions your device supports, you can also use "Write Multiple Coils" (Modbus function 15) to write contiguous bits, or "Mask Write Holding Register" (Modbus function 22) to write a register partially.