Appendix A: Troubleshooting Table - Eaton CROUSE-HINDS Series Instruction Manual

APPENDIX A: TROUBLESHOOTING TABLE

Symptom
High peak or average noise
Recommendations: Inspect the network cable and connections. Tighten screw terminals and connector hold-down screws. Look for
waterlogged cables, condensation in junction boxes, loose wires, FF cable routed near other signaling cables or AC power cables, loose
strands of wire shorting to other wires/conductive objects. Check if fieldbus to shield short is present and if so follow recommendations
below. Verify the segment is powered by an isolated fieldbus power supply or that the bulk supply for the fieldbus power supply is isolated
and only powers one segment. Take noise measurements at multiple locations on the network to identify where noise is highest and most
likely located. Measure resistance from shield to ground with a DMM and verify it is <100Ω. Disconnect devices one at a time to see if
noise disappears. Replace terminators, fieldbus power supplies, and wiring blocks.
Symptom
Excessive retransmissions rate
(on one device)
Recommendations: Check if high noise levels are present and if so follow recommendations above. If the wiring block has a current
limiting (SpurGuard) feature, check the associated LED to make sure it isn't constantly or intermittently lit. Inspect the wiring and connections
from the wiring block to the device looking for waterlogged cables, condensation in junction boxes, loose wires, FF cable routed near
other signaling cables or AC power cables, loose strands of wire shorting to other wires/conductive objects. Try putting the device on a
different spur from the wiring block. Replace the device.
Symptom
Excessive retransmissions rate
(on all or multiple devices)
Recommendations: Determine if the entire network is affected or just part of it. Focus on the part of the network with problems. Check
if high noise levels are present and if so follow recommendations above. Use the FBT-3/6 to check for high noise levels at the device
and check the bus voltage is >9VDC at the device furthest from the power supply. Inspect the network looking for waterlogged cables,
condensation in junction boxes, loose wires, FF cable routed near other signaling cables or AC power cables, loose strands of wire shorting
to other wires/conductive objects. Replace the terminators, power supply/conditioner.
Symptom
Low device signal level
(one device)
Recommendations: Use FBT-3/6 to check the voltage at the device is >9VDC. If the wiring block has a current limiting (SpurGuard)
feature, check the associated LED to make sure it isn't constantly or intermittently triggered. Inspect the wiring and connections from
the wiring block to the device looking for waterlogged cable, condensation, loose wires, loose strands of wire shorting to other wires/
conductive objects. Verify the maximum length of cable between any 2 devices does not exceed 1900m and spur length does not exceed
120m. Try connecting the device on a different spur from the wiring block. Replace the device.
Symptom
Low device signal level
(all devices)
Recommendations: Use FBT-3/6 to check the voltage at the device furthest from it is >9VDC. Check the power LEDs on the wiring
blocks are steadily lit. Inspect the wiring and connections (especially at the parts common to all devices such as power supply/conditioner,
terminators, trunk cable, etc.) looking for waterlogged cable, condensation, loose wires, loose strands of wire shorting to other wires/
conductive objects. Replace suspect physical layer components (power supply/conditioner, terminators, wiring blocks).
Symptom
High device signal level
(one device)
Recommendations: Replace the device.
Symptom
High device signal level
(all devices)
Recommendations: Verify two terminators are installed (note that some terminators are built-in to power supplies/conditioners and
wiring blocks, some are turned on/off with a switch and some are automatic). Check wiring to the terminators. Replace suspect terminators
or the products that contain them. Replace the fieldbus power supply.
INM F809F-2C rev 2
Possible Causes
Water/condensation in wiring, improperly connected shield, bad fieldbus device, bad physical
layer component (power supply, terminator, wiring block), segment is not isolated from ground,
fieldbus cable is located near noise producing cable, loose wire termination.
Possible Causes
Bad spur wiring connection to device, not enough power to the device, bad device, bad port on
the wiring block, noise on the spur.
Possible Causes
Wiring problem, not enough power to the devices, bad physical layer device (power supply,
terminator, wiring block), noise on the bus
Possible Causes
Bad spur wiring connection to device, not enough power to the device, bad device, bad port on
the wiring block
Possible Causes
Wiring problem, not enough power to the devices, bad physical layer device (power supply,
terminator, wiring block)
Possible Causes
Bad device
Possible Causes
Missing terminator, failed terminator, improperly connected terminator, failed fieldbus power
supply
20 20