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LOI Mode

The SS20's LOI mode allows a dedicated local operator interface (LOI) connection to devices connected downstream of the SS20 without requiring disconnection of existing field wiring. The USB interface allow maintenance to be performed on both RS-232 and RS-485 devices using modern laptop computers lacking DB9 serial ports and no additional USB-to-serial converters or RS-485 converters are required.

When the hardware's USB Mode switch is set to 'LOI' the SS20 detects when a USB cable is plugged into the device and automatically blocks traffic from both input COM ports while directing traffic from the USB connection directly to the output ports of the SS20.

The operator can then connect to the downstream devices using their associated programming software or any third party serial maintenance or diagnostic software desired by using the VCP port number assigned to the SS20 by the PC. (see for more information). The VCP port will show up in the third party application as a available com port and will function the same as if it was connected to a native serial port. The Baud rate and data format will be set by the application and should match the end devices rate and format.

Once the USB cable is un-plugged or the USB Mode switch is switched to either TAP or GUI the device will automatically resume normal operation.

loi.txt · Last modified: 2017/07/23 21:38 by dmeier