QIRF Operation And Maintenance Manual
QIRF Operation Manual
May. 01, 2012
85050-301-000 Rev C
10
2.4.3 Wire and Cable
The terminal block plug TB1 accepts 12 AWG to 24 AWG wire, Use 16 AWG or 18
AWG wire for Power Supply in long wiring runs, which can be up to 1km (1,000 meters)
long.
We recommend using BELDEN 9841 for communications. This wire has 120 ohm input
impendence, which will eliminate RS-485 communication problems.
2.4.4 Digital Connection
2.4.5 RS-485 Terminator
The terminator on each end of the RS485 loop is designed to match the electrical
impedance characteristic of the twisted pair loop, and will prevent signal echoes from
corrupting the data on the line. The terminator should be enabled on BOTH ends of the
RS485 loop. Short and medium length modbus/485 loops can operate without the
terminating resistor. Longer runs may require the terminating resistors. But adding
terminator dramatically increases power consumption.
Factory default setting is disabled terminator
.
The QIRF smart sensor supplies this resistor on the display board, and it is chosen using a
jumper at J3.
•
J3 1-2: Terminator Disabled / OFF (default)
•
J3 2-3: Terminator Enabled / ON
