Troubleshooting, continued
87
Problem The optional (rain or alarm) sensor is not responding.
Solution Disconnect the two-wire sensor connection from the terminals inside the controller. After a
few seconds, a message should appear on the controller’s display screen reading, Rain (or
Alarm) Sensor In:<time>. Next, connect a piece of wire between the terminals. The message
should change to Out:<time>. This sequence is based on a correct set up and a rain (alarm)
sensor that is Normally closed (NC). (ON, open = NC; ON, closed = NO—Normally open). If this
sequence does not occur, check to make sure the rain (alarm) sensor is properly installed.
Please see Connecting an Optional Sensor on page 13.
Troubleshooting a Field Transmitter (Optional)
The Field Transmitter is a separate, small, handheld computer, which uses special connectors to connect to the
two-wire communications cable in the field. You use Field Transmitters to manually operate field decoders. In the
following, it is assumed that the MDC Controller and field decoder system is working properly.
Problem The Field Transmitter’s display is dead.
Solution Check that there is line voltage on the connection sockets inside the Field Transmitter
Connection Box. Various connection boxes may be located in the field at specific points along
the two-wire communications line. Use the irrigation drawings to find the location of each box.
Open the Connection Box and measure the line voltage between terminals 1 and 2. Make sure
the wires leading into the rear terminals are not corroded. If they are, cut away the corroded
wires and reconnect the wires.
Check the connection points. If the pins of the socket are corroded (which can happen if the
protective cap is missing) replace the socket.
Problem The Field Transmitter reads No Contact.
Solution A No Contact message indicates the Field Transmitter cannot contact the controller. Heavy
leakage currents may cause this in the system. Check the line voltage. If the line voltage is
acceptable, there is probably a fault in the Field Transmitter, or in rare cases, the controller.
Check the Field Transmitter’s installation data. Make sure PULSE TIME is set to 0 and INT.
DELAY is set to 4O. Please see the Field Transmitter User Manual on page 43. If these settings
are correct, replace the Field Transmitter.
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