Rockwell Automation 1772-L8_LW_LWP_LX_LXP,D17726.5.8 User Manual - Manual (Page 400)

Chapter
26
26-1
Program Troubleshooting
This chapter describes special troubleshooting technique:
run time errors
bit
monitor/manipulation
contract histogram
force functions
temporary end instruction
ERR message for an illegal opcode
The processor and the 1770-T3 Industrial Terminal can diagnose certain
errors that occur during the execution of your program.
What are Run Time Errors?
Run time errors are errors that occur while the processor executes your
program, and are only apparent during this time. These errors result from
improper programming techniques. For example, it is possible to program
a series of instructions that the processor cannot properly perform. Or, it is
possible to program paired instructions, such as a Jump/Label, with
improper syntax.
If a run time error occurs and your processor is in the Run or Run/Program
mode, the processor’s green run LED goes out and it displays a run time
error. The instruction with the illegal data is intensified on the industrial
terminal screen, after re-entering the PLC-2 mode from the mode selection
screen. The processor is automatically placed in the Remote Program
mode. After you correct the program, change the mode select switch from
Run or Run/Program to Program mode and then to Run or Run/Program
mode. Or, you can cycle power in the Run mode to get the processor
running again (if the processor’s keyswitch is in the Run mode).
Chapter Objective
Run Time Errors