
Troubleshooting
Appendix B
B-6
Consult Table B.E to identify PLC communication problems.
Table B.E
PLC
Communication Problems
Problem Cause What to do
PLC Communication Lost" message on
PanelView terminal.
PLC controller is in Program or Remote Program
mode.
Change PLC controller to Run mode.
Cable problem. Check termination and cable pinout.
Incorrectly defined terminal as Last Chassis. Set Last Chassis to No for that rack assignment.
Rack assignments in PanelView and PLC do not
match.
Make sure rack assignments in PLC controller
match those in PanelView.
Terminating resistor not installed properly. The terminating resistor must be installed at the
PLC and at the end of the link:
150W 1/2 watt resistor for 57.6 or 115.2 kbaud
82W 1/2 watt resistor for 230 kbaud
PanelView terminal and Scanners Remote I/O
baud rate do not match.
Change the Remote I/O baud rate in PanelView
terminal or the scanner so they match.
PLC Communication Lost" message when
using PanelView terminal with PLC5.
PanelView terminal has been assigned to
multiple or partial racks when firmware revision
of PLC5 does not support partial rack
addressing.
Configure PanelView terminal as a single full
rack.
Upgrade PLC5/15 to Series B Revision H.
Upgrade PLC5/25 to Series A Revision D.
PLC controller is not configured to recognize the
PanelView terminal's rack assignments.
Refer to your PLC5 User's Manual regarding
Auto Configuration.
Periodic PLC Communication Lost" when
using 1772SD2 scanner with PLC2s.
Must use 1772SD2 scanner Rev. 3 or later.
Rapid blinking of PLC Communication Lost"
when using 1775S4A scanner with a PLC3.
Must use 1775S4A scanner series B or later.
PLC Communication Lost" when using SLC
500 1747SN Scanner Module.
The 1747SN Scanner Module is not properly
configured.
Refer to 1747RIO Scanner User's Manual
regarding Specialty I/O Configuration and how to
configure Mfiles and Gfiles.
Verify that the PanelView terminal and the
1747SN Scanner Module Remote I/O baud
rates are set the same.
Discrete I/O works but block transfer does
not. No PLC Communication Lost"
message. Using PLC5/15, partial rack
addressing.
Must use PLC5/15 series B Rev. J or later.
Discrete I/O works but block transfer does
not. No PLC Communication Lost"
message.
Block transfer assignments in PanelView do not
match block transfer instructions in PLC.
Make sure PLC block transfer instruction
parameters match PanelView parameters.
PLC Controller rack fault on rack assigned to
PanelView.
Specified No for Last Chassis when the
PanelView is the last chassis in that rack.
Set Last chassis to Yes for that rack assignment.
PLC Communication Lost" message and
rack fault on rack assigned to PanelView.
Mismatched baud rate on PanelView and PLC
controller.
Specify same baud rate for PanelView and PLC
controller.
Multiple devices configured for the same rack
assignment.
Multiple remote I/O devices must have unique
rack assignments.
PLC Communication Problems
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