EasyGrid Base User Guide v1.0
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5.6 RS-485 / RS-422
Please refer to the Communication Configuration section for dip switch settings
The EasyGrid Base RS-485 / RS-422 communication port is half duplex.
FISO recommends the use of a two shielded twisted pair cable for RS-485 mode and a three shielded
twisted pair cable for RS-422. The extra pair will be used for ground.
If the EasyGrid Base is at one end of the cable you must place an End of Line resistor. You can use the
integrated EOL resistance with the OFF / EOL dip switch.
FISO recommends polarising the link in one place. You could use the integrated pull up and pull down
resistors of the EasyGrid Base. To do so, place the Pull Up and the Pull Down dip switch to the top.
A and B Circuit Designators:
The ‘A’ and ‘B’ circuit designators are often a source of confusion.
To determine which terminal is ‘A’ and which is ‘B’, set the line to the ‘Idle’ or ‘Off’ state. Connect a multi-
meter on the volts range across the ‘A’ and ‘B’ terminals. When the multi-meter reads a positive voltage, the
positive terminal of the multi-meter is connected to ‘B’ and GND terminal is connected to ‘A’.
This is why we write ‘B+’ and ‘A-’ on the EasyGrid Base.
It is important to refer to the manufacturer’s handbook or to test the line as in the previous paragraph.
RS-422 Wiring