Instrument Control (GPIB, Serial, VISA, IVI)

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Modbus Serial RTU write and read

Hi everyone, first time posting here, not and experienced user but I will try to explain. I am trying to communicate with an inverter of an hydraulic pump through a usb-rs485 converter using modbus protocol. I have to perform both writing and reading operations, setting the speed of the pump and reading several parameters. In order to do this I'm using MODBUS API in labview version 2019. When I used the write and read multiple holding registers I keep getting the same error 56 timeout. So I tried to program 2 different VIs. The first one where I just try to read the holding registers and the second one where I try to write. In the former case no error occurs. In the second one timeout happens. In order to force the code I used also the clear error function because I noticed that before the error message appear the pump starts running. Highlighting the execution I noticed that the error occurs roughly once every 2 iterations of the while loop. Any help would be appreciated.

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