Distech Controls ECB-VAV, User Manual

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116 Network Guide
Power supply polarity Verify that consistent polarity is maintained between all controllers and the trans-
former. Ensure that the COM terminal of each controller is connected to the same
terminal on the secondary side of the transformer. See
Power Supply Require-
ments for 24V Controllers on page 61.
Controller communi-
cates well over a short
network, but does not
communicate on large
network Network length Check that the total wire length does not exceed the specifications of the Network
Guide. See
Data Bus Physical Specifications and Cable Requirements on page
151.
Wire type Check that the wire type agrees with the specification of the Network Guide: See
Data Bus Physical Specifications and Cable Requirements on page 151.
Network wiring prob-
lem Double check that the wire connections are correct.
Absent or incorrect
network termination Check the network termination(s). Incorrect or broken termination(s) will make the
communication integrity dependent upon a controller's position on the network.
Extra capacitance Make sure that no extra capacitance is being connected to the network other than
the standard FTT circuit, and a maximum of a 3 meter stub (in bus topology).
Number of controllers
on network segment
exceeded The number of controllers on a channel should never exceed 50. Use a router or
a repeater: See
Data Bus Segment MAC Address Range for BACnet MS/TP
Devices on page 148.
Network traffic Query node statistic to check errors.
Use a LON protocol analyzer to check network traffic.
Hardware input is not
reading the correct
value Input wiring problem Check that the wiring is correct according to the module's hardware installation
manual and according to the peripheral device's manufacturer recommendations.
Open circuit or short
circuit Using a voltmeter, check the voltage on the input terminal. For example, for a dig-
ital input, a short circuit shows approximately 0V and an open circuit shows
approximately 5V. Correct wiring if at fault.
Configuration problem Using the controller configuration wizard, check the configuration of the input.
Refer to the controller's user guide for more information.
Over-voltage or over-
current at an input An over-voltage or over-current at one input can affect the reading of other inputs.
Respect the allowed voltage / current range limits of all inputs. Consult the appro-
priate datasheet for controller input range limits.
Hardware output is not
operating correctly Fuse has blown (Auto
reset fuse, for 24V
controllers) Disconnect the power and outputs terminals. Then wait a few seconds to allow
the auto-reset fuse to cool down. Check the power supply and the output wiring.
Reconnect the power.
Output wiring problem Check that the wiring is correct according to the module's hardware installation
manual and according to the peripheral device's manufacturer.
Configuration problem With EC- gfx Program, check the configuration of the output; for example, is it
enabled? Refer to the EC- gfx Program User Guide for more information.
Table 32: Troubleshooting ECL Device Symptoms
Symptom Possible Cause Solution