Symptoms that you might see in Diagnostics such as communication errors,
commissioning failures, commissioned devices transitioning to decommissioned or
disappearing and reappearing on the segment can be caused by:
- Improper firmware revision
for the H1 card. Run the DeltaV Controller Upgrade Utility to upgrade the
controller and correct this problem. Click
and follow the instructions to
upgrade I/O and controllers.
- Terminator switches set
incorrectly. Correct the termination. Remember that there must be only two
terminators per segment.
- Improper wiring or
incorrectly installed terminators. Correct the wiring and termination by:
- Grounding the shield
only in one place, preferably the DeltaV system cabinet. Use shielded,
twisted-pair cable.
- Cutting and taping the
shield inside the instrument housing to prevent the shield from contacting the
instrument housing and possibly causing a ground loop.
- Wiring all spurs in
parallel (individually or as a group in a junction box, including the shield).
If the wiring between the H1 card and the power supply uses untwisted,
unshielded power cable, excessive noise can occur.
- Continuing the twisted,
shielded pair all the way back to the H1 card and ground the shield at the
ground bus bar on the 8-wide I/O carrier
- A faulty power supply.
Replace the unit.