Specifications

Counter Preload Program Example
To preload the counter, just add the following example rungs to the program above.
Troubleshooting Guide for HSIO Mode 20
If you’re having trouble with Mode 20 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 or other field device inputs actually turn on and
illuminates the status LEDs for X0 and X1. A standard incremental encoder will visibly, alternately
turn on the LEDs for X0 and X1 when rotating slowly (1 RPM). Or, the problem could be due to
a sinking-sourcing wiring problem, etc. Remember to check the signal ground connection. Also
verify that the pulse on-time, duty cycle, voltage level, and frequency are within the input
specifications.
2. Configuration – make sure all of the configuration parameters are correct. V7633 must be set to
20, and V7634 must be set to “0002” to enable the Phase A input, and V7635 must be set to
“0000” to enable the Phase B input.
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 and must be off for the counter to count. The bottom input is the counter reset, and
must be off during counting.
Symptom: The counter counts in the wrong direction
(up instead of down, and visa-versa).
Possible causes:
1. Channel A and B assignment – It’s possible that Channel A and B assignments of the encoder
wires are backwards from the desired rotation/counting orientation. Just swap the X0 and X1
inputs, and the counting direction will be reversed.
Symptom: The counter counts up and down 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. Also verify
the configuration register V7636 for X2 is set to 7. 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–23
Appendix E: High-speed Input and Pulse Output Features
1
2
3
D
E
6
7
8
9
10
11
1
1
14
A
B
C
D
X
4
RST
W
hen the preload request is made, the user turns
on X4. First we disable counting by resetting C0,
the counter ’s enable input.
C0
PD
Generate a preload counter input pulse, which
causes the counter to preload from V1076-V1077.
C1
LDD
K3000
Load the BCD value K3000 into the
accumulator.
OUTD
V1076
Output the constant to V1076/V1077, the location
of the accumulated pulse count.
Preload counter
C1C0
SET
C0
Enable the counter by setting C0, when the
preload pulse on C1 has occurred (C1 is of
f).