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4.1 Troubleshooting Guide
Malfunction or incorrect operation may be caused by:
1.
Incorrect Readings:
Check for improper wiring using
Figure 2-2
as a guide.
2.
Loose or broken wires:
Check each terminal connection for tightness. Move each wire
back and forth and note any changes in operation.
3.
Too high a load resistance in the output current loop or too low a
current rating on the power supply:
a)
Measure the total resistance of each device (excluding the
transmitter and power supply) in the 20 mA loop, including
the resistance of the lead wires.
b)
Calculate maximum allowable loop resistance using the
formula: Loop Resistance (maximum) = Vsupply – 8 V
0.020A
For example
, a 24V power supply would give a maximum loop
resistance of: 16 V/0.020A = 800 ohms.
c)
Make sure the power supply is rated for at least 28 mA
times the number of transmitters being powered. For
example, if the supply is powering five transmitters, the
supply should be rated for at least 140mA.
