OPTO 22 Optomux B1, Руководство пользователя

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APPENDIX B: TROUBLESHOOTING
B1 and B2 User’s Guide
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labeled UPPER (closest to module), and if the module has terminals on the top of the
module, connections would be made there. Analog racks have the terminal channels
labeled from 1 to 4 (or 16). These channels correspond to module positions 0 to 3 (or 15)
respectively.
f. If all inputs on that board have the same -4,096 reading, then check to make sure the board
has +15 and -15 VDC at the corresponding terminals (with reference to the terminal that is
marked COMMON).
Q. I receive a large number of checksum errors (N02) when I send commands to an Optomux unit.
A. Make sure that you are using twisted pair cable. The RS-422/485 network is only reliable when
the communications cable is twisted (+ and - lines of EACH pair twisted together) with at least 1/2
twist per inch. Sometimes, the wire is twisted but one of the connections of a pair is actually used as
the mate to the opposite pair ( - of one pair used as - of opposite pair). This cross-twist condition is
usually due to jacketed twisted pair cables, which have a wire of each pair with the same color code.
In this case, strip the jacket back far enough to properly identify the individual pairs.
You should also check the Group A jumpers to make sure the termination and bias jumpers are
correctly installed.