Appendix B
RS-485 Output
The sensor module uses an RS-485 serial interface with Modbus
protocol. To communicate to the RS-485 output via a computer
interface, an isolated RS-485 converter (such as P/N 10014359) should
be used. The baud rate is 19,200 baud with RTU format sent. Each byte
has eight bits with no parity and two stop bits. Each exchange has a
two-byte CRC 16 check value.
The sensor unit has an ID range of 100 - 107. The dip switch positions
1 through 3 are binary encoded and read on startup.
Table B-1. Dip Switch Positions
ID DIP SWITCH
1234
100 0 0 0 -- *
101 100--
102 010--
103 110--
104 0 0 1 -- *
105 101--
106 011--
107 111--
NOTE: 1 indicates closed.
* indicates valid address for a four-point pumped unit.
Two functions are supported:
• Read Holding Registers - Function #3
• Preset Multiple Registers - Function #16
B-1
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