Specifications

Troubleshooting Guide for Mode 10

If you’re having trouble with Mode 10 operation, please study the following symptoms and

possible causes. The most common problems are listed below.

Symptom: The counter does not count.

Possible causes:

1. Field sensor and wiring – Verify that the encoder, proximity switch, or counter actually turns on

and illuminates the status LED for X0. The problem could be due to sinking-sourcing wiring

problem, etc. Remember to check the signal ground connection. Also verify that the pulse on-time

is long enough for the PLC to recognize it.

2. Configuration – use the Data View window to check the configuration parameters. V7633 must

be set to 10, and V7634 must be set to 1 to enable the HSIO counter mode.

3. Stuck in reset – check the input status of the reset input, X2. If X2 is on, the counter will not

count because it is being held in reset.

4. Ladder program – make sure you are using counter CT76 in your program. The top input is the

enable signal for the counter. It must be on before the counter will count. The middle input is the

dummy input. The bottom input is the counter reset, and must be off during counting.

Symptom: The counter counts but the presets do not function.

Possible causes:

1. Configuration – Ensure the preset values are correct. The presets are 32-bit BCD values having a

range of 0 to 99999999. Make sure you write all 32 bits to the reserved locations by using the

LDD and OUTD instructions. Use only even–numbered addresses, from V2320 to V2376. If

using less than 24 presets, be sure to place “0000FFFF” in the location after the last preset used.

2. Interrupt routine – Only use Interrupt #0. Make sure the interrupt has been enabled by executing

an ENI instruction prior to needing the interrupt. The interrupt routine must be placed after the

main program, using the INT label and ending with an interrupt return IRT.

3. Special relays – Check the special relay numbers in your program. Use SP540 for Preset 1, SP541

for Preset 2, etc. Remember that only one special equal relay contact is on at a time. When the

counter value reaches the next preset, the SP contact which is on now goes off and the next one

turns on.

Symptom: The counter counts up but will not reset.

Possible causes:

1. Check the LED status indicator for X2 to make sure it is active when you want a reset. Or, if you

are using an internal reset, use the status mode of DirectSOFT 5 to monitor the reset input to the

counter.

DL05 Micro PLC User Manual, 6th Edition, Rev. C

E–17

Appendix E: High-speed Input and Pulse Output Features