ICP DAS USA GRP-530M User Manual page 61

(8) You will see virtual com port: COM32, COM33, but it can't be opened.
Click "tool"/"Restart Driver" to restart VxComm driver.
Open com port to connect your device.
(In this case, COM32 is RS-232, COM33 is RS-485 of GRP device. Please don't open
COM33, because it's Modbus/TCP to Modbus/RTU mode)
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GRP-530M / GRP-540M User Manual Version 1.2.0 Page：
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