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 sensor actually turns on

and illuminates the status LED for X0 (counter 1) and X1 (counter 2). 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 or 101 to enable the first high-speed counter. V7635

must be set to 1 or 101 to enable the second high-speed counter.

3. Stuck in reset – check the input status of the reset input, X2 and X3. 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 CT174 and CT176 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 V3630 to V3767. If

using less than 24 presets, be sure to place “0000FFFF,” “0000FF00,” or “000000FF” 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 (counter 1) and X3 (counter 2) 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 to

monitor the reset input to the counter.

DL06 Micro PLC User Manual, 3rd Edition, Rev. C

E–23

Appendix E: High-speed Input and Pulse Output Features