
IM-P505-02-US
Issue 1
36
UTM20 Series Ultrasonic Transit-time Flowmeters
8.12 RS485 Output
The RS485 feature allows up to 126 transmitters to be placed on a single three-wire cable up to 4000
feet. All transmitters are assigned a unique numeric address that allows all of the transmitters on the
cable network to be independently accessed. Either Modbus RTU or BACnet MS/TP protocol is used
to interrogate the transmitters.
Flow rate and total can be monitored over the digital communications bus.
When a USB programming cable is connected, the RS485 and frequency outputs are disabled.
Fig. 39 Typical RS485 interface
8.13 Digital Input Wiring
Fig. 40 Digital input—reset totalizer
Terminator Resistors
(Enabled through Parameter Setting)
60.4 Ohms 60.4 Ohms
A B
TB700
3
4
RS485 +
RS485 −
External Equipment
TB700
1
2
3
4
5
6
7
8
9
10
Reset Total +
Reset Total -
Push-button
5 to 30V DC