296 T1/T1S User’s Manual
10. Troubl eshooting

10.1.2 CPU check

If the PWR ( power) LED is lit but the RUN LED is not lit , check the following points.
Check the position of the If it is not in R (RUN) position, turn the
mode control switch switch to R (RUN) position.
Check the FLT (fault) LED If the FLT LED is lit or blinking, the T1/T1S
is in the ERROR mode. Confirm the error
message by connecting the programming
tool. Refer to section 10.2.
Is the RUN LED blinking ? If it is blinking, the T1/T1S is in the HOLD
mode. Check your program whether the
HOLD device (S401) is not used.
Connect the programming If the T1/T1S stays in HALT mode even
tool, and check the T1/T1S’s when the mode control switch is changed,
status the switch may be faulty.
If the communication between the T1/T1S
and the programming tool is not possible,
the T1/T1S may be faulty.

10.1.3 Program check

Check the user pr ogram based on the following points if it is running but the operation
does not work as intended.
1. Whet her duplicat ed coils ar e not programmed.
2. Whet her a coil device and a destination of a f unct ion inst r uction are not overlapping.
3. Whet her t he ON/OFF duration of an external input signal is not shorter t han the
T1/T1S’s scan time.
4. Whet her a r egister/device which is used in the main prog r am is not operated
erroneously in the inter r upt pr ogram.
NOTE When you write/ m odify the program, it is necessar y to execute the EEPROM
write operation before turning off power to the T1. O therwise the old program
stored in t he built - in EEPRO M will be over-written, and your program
modif icat ion will disappear.
CTi Automation - Phone: 800.894.0412 - Fax: 208.368.0415 - Web: www.ctiautomation.net - Email: info@ctiautomation.net