Specifications

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12.0 TROUBLE-SHOOTING
If after 10 min of operation there are errors in the system the following check list should be carried out.
1) Check that there is adequate power on the system.
a) 120VAC (main control board)
b) 24VDC line on the system wiring run (at each DST)
2) Check that all the link (amber) lights are “on” (DST’s and other external circuit boards).
3) Check that there are no open loops on the analog inputs (analog systems only).
4) Check that the wiring is correct at the system wiring terminals and analog inputs .
5) Check that there is proper termination on both ends of the system wiring run. This includes each node.
NOTE: A node is a branch circuit where a bridge has been installed on the bus.
With the POWER “OFF” check the following
1) Check that there in infinite resistance between the 24VDC and the ground (COM) on the system wiring.
2) Check that remote power supplies inputs have been correctly wired (parallel) to the system at a DST or CNB bridge.
3) Check that there is infinite resistance between the signal lines data-A and data-B and the ground (COM) on the system wiring.
4) Check that there is infinite resistance between the Signal lines data-A and data-B.
NOTE: If termination (jumpers) has been placed on the CNB bridges or DSTs then the resistance should be either 60 ohms or 30
ohms depending on the value on the termination resistor.
With the POWER OFF
1) Checking the Signal lines data-A and data-B: In order to check that the data-A and data-B wires are correctly wired to the proper inputs
the following procedure can be used
a) Remove all termination jumpers.
b) At one end of the branch circuit tie the data-A line (short) to the common (COM). This can be accomplished by pulling the A line
out of its position in the terminal block and inserting it, along with the common wire into the COM position on the terminal block
c) Measure the resistance across the data-A line and the COM at the other end of the branch circuit. This should be short (zero
resistance). IF NOT then there is a break in either the data-A line or the COM wire.
d) Measure the resistance between the data-B line and the COM. This should be infinite resistance. IF NOT then there is a cross in
the wires some where.
e) Replace the data-A wire back into the data-A position on the terminal block.
f) Carry out the same procedure with the data-B wire. The resistance between the data-B wire and the COM at the other end of the
node should be zero and the resistance between the COM wire and the data-A wire should be infinite.
g) Reconnect the data-B wire to the data-B position in the terminal block and replace the termination jumpers.
h) Check that there are no shorts between the 24VDC and COM.
I) Check that there is either infinite resistance between data-A line and COM and the data-B line and COM. If there are termination
jumpers installed this should be either 60 or 30 ohms depending on the termination resistors installed.