High-Speed Input and
Pulse Output Features
3–17
High-Speed Input and Pulse Output Features
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 to monitor the reset input to the counter.
Troubleshooting
Guide for Mode 10
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