AMC-UTx-M-xx-400 Series Digital Transmitter
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4.3.1 POWER
The UTx-M-400 is 24VDC powered and has a minimum UTx-M operating voltage of 10.5 Volts.
The table below indicates the maximum number of usable units for various wire gauges and
distances between units to ensure properly operating voltage. Using lower number of units for the
gauge and distance will allow UTx-M-400 unit to operate correctly.
Please consult with Armstrong Monitoring for maximum number of usable unit for other gauges
or greater distances.
Table 4-1 Units vs Gauge/Distance
Average distance
between units
and Gauge
75ft
150 ft
200 ft
16AWG
18AWG
16AWG
18AWG
16AWG
18AWG
Number of Units
27
21
19
15
16
13
Total Current
1.49A
1.16A
1.05A
0.83A
0.88A
0.72A
Caution:
Care must be taken when installing to ensure that all UTx-M-400s are connected with
the same power supply polarity across the network. Digital Trans should be
connected to +24VDC power terminal at monitor and Digital Transmitter - should be
connected to SGND power terminal at monitor.
4.3.2 COMMUNICATION
The total communication cable length for a network segment should not exceed 1000 M (3280 ft)
without the use of repeaters.
There is a 32 unit load (UL) transmitter limit per RS-485 bus segment determined by
ANSI/TIA/EIA-485-A-1998 standard. The AMC-1DBx Digital Monitor uses one RS-485 unit load,
so only 31 additional RS-485 unit loads can be driven on each MODBUS Network Segment. Note
that each device and the repeaters use a UL on each input.
The AMC-1DMB-PS-R Repeater is required to expand beyond this 32 UL limit configuration limit
per MODBUS and requires a unit load itself.
Caution:
Care must be taken when installing to ensure that all Digital Transmitters are
connected with the same Modbus polarity across the network. Digital Monitor RS485A
should be connected to the UTx-M A1 terminal and Digital Monitor RS485B should be
connected to the B1 terminal. If required, the UTx-M Menu provides an option to invert
the A and B signals on the transmitter to resolve wiring mismatches; refer to Section
5.2.1 for details.
