16 • Chapter 3: Installation
AirLink 9850 Gas Monitor Operator’s Manual
RS-485 Modbus Wiring (Modbus Out)
NOTE:
The AirLink 9850 outputs RS-485
OR
RS-232, depending on the “485 or 232” setting in the
Modbus settings menu (see page 27). The AirLink 9850 must be set up to generate the desired
output.
1. Open the enclosure box to expose the Front Panel.
2. Unscrew the two thumb-screws on the Front Panel.
3. Open the Front Panel so that the back of the Terminal Board is exposed.
4. Locate the Modbus Out Terminal Block.
5. Connect a red wire from a PLC’s RS-485 A (+) terminal to the terminal labeled “A” on the
Modbus Out Terminal Block.
6. Connect a green wire from a PLC’s RS-485 Ground terminal to the terminal labeled “GND” on the
Modbus Out Terminal Block.
7. Connect a black wire from a PLC’s RS-485 B(-) terminal to the terminal labeled “B” on the
Modbus Out Terminal Block.
Figure 7: Modbus Out Wiring
8. Close the Front Panel.
9. Screw in the thumb-screws.
10. Close the enclosure box.
11. Clamp down the enclosure latches.
