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34 Point Multiplex Modules—Multiplex Binary
If the transmit LED never lights, check if the green RECV (receive)
LED lights.
-
If the RECV LED does not light, the XBN is not receiving data
from the N2 Bus and therefore is not connected properly to the
N2 Bus. Refer to the N2 Communications Bus Technical Bulletin
in this manual.
-
If the RECV LED does light without the XMIT LED ever
responding, perhaps no messages are being addressed to the XBN.
Ensure that the system is configured to poll the XBN by cross
checking the address in the Hardware Definition window with the
address physically set by the N2 address switches. If the address is
changed, cycle power to the XBN after resetting the N2 address
switches.
4. Ensure that the input LEDs on the XBN coincide with the "present
state" indication at the NCM. This requires a comparison of the
point's status as seen on the Object Focus window with the actual
condition of the LED. Note that the LED orientation is used defined in
software, such that the LED light On may indicate either contact
closed/voltage present or contact open/voltage absent.
5. Force each binary input to change state, then check: a) the "present
state" condition on the Object Focus window or the Network Terminal
and b) the LED light to verify that the change was detected
accordingly.
Note: Steps 4 and 5 require that the point data base has been
downloaded to the XBN. If no point data base download has
ever been made, the LED lights will not indicate the point
status.
If the XBN fails the Field Checks, replace the module. There are no test
points or removable parts on the XBN. The only field repair is to replace
the module.
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