ICP DAS USA GRP-520 User Manual page 51

GRP-520 User Manual, V1.30, Aug. 2015
(8) You will see virtual com port: COM11, COM12, but it can't be opened.
Click "tool"/"Restart Driver" to restart VxComm driver.
Open com port to connect your device.
(In this case, COM11 is RS-485, COM12 is RS-232 of GRP-520.)
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