Maintenance
and Troubleshooting
9–2
Maintenance and Troubleshooting
Hardware System Maintenance
No regular or preventative maintenance is required for this product (there are no
internal batteries); however, a routine maintenance check (about every one or two
months) of your PLC and control system is good practice, and should include the
following items:
S Air Temperature – Check the air temperature in the control cabinet, so
the operating temperature range of any component is not exceeded.
S Air Filter – If the control cabinet has an air filter, clean or replace it
periodically as required.
S Fuses or breakers – Verify that all fuses and breakers are intact.
S Cleaning the Unit – Check that all air vents are clear. If the exterior
case needs cleaning, disconnect the input power, and carefully wipe the
case using a damp cloth. Do not let water enter the case through the air
vents and do not use strong detergents because this may discolor the
case.
Diagnostics
Your DL05 Micro PLC performs many pre-defined diagnostic routines with every
CPU scan. The diagnostics can detect various errors or failures in the PLC. The two
primary error classes are fatal and non-fatal.
Fatal errors are errors which may cause the system to function improperly, perhaps
introducing a safety problem. The CPU will automatically switch to Program Mode if
it is in Run Mode. (Remember, in Program Mode all outputs are turned off.) If the fatal
error is detected while the CPU is in Program Mode, the CPU will not allow you to
transition to Run Mode until the error has been corrected.
Some examples of fatal errors are:
S Power supply failure
S Parity error or CPU malfunction
S Particular programming errors
Non-fatal errors are errors that need your attention, but should not cause improper
operation. They do not cause or prevent any mode transitions of the CPU. The
application program can use special relay contacts to detect non-fatal errors, and
even take the system to an orderly shutdown or switch the CPU to Program Mode if
desired. An example of a non-fatal error is:
S Particular programming errors
The programming devices will notify you of an error if one occurs while online.
S DirectSOFT provides the error number and an error message.
S The handheld programmer displays error numbers and short
descriptions of the error.
Appendix B has a complete list of error messages in order by error number.
Many error messages point to supplemental V-memory locations which contain
related information. Special relays (SP contacts) also provide error indications.
Standard
Maintenance
Diagnostics
Fatal Errors
Non-fatal Errors
Finding Diagnostic
Information
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