HMC7000 Series I/O Module Guide
87
HMC7000 Series I/O Module Guide
87
Some Sample Ladder Logic
These two rungs configure the High Speed Counters in a unit that has built-in I/O.
The HMC ladder logic requires an input condition on each rung. The input bits are the Normally Closed contacts
of an otherwise unused bit. The Move Word instructions write a value of 2 (00000010
b
) to the Configuration
Register of each High Speed Counter. This sets Bit 1 and leaves all other bits reset. Each counter is configured
as a High Speed Up Counter, with the trigger being on the falling edge.
The trigger is configured by Bit 3 of the Configuration Word. To configure the trigger as a rising edge, write 10
(00001010
b
) to the Configuration Register.
Retaining the High Speed Counter Values
The Count and Preset values are normally lost when power is removed from the HMC. However, the System
Parameters dialog has an option to retain the Count and Preset values.
Click System parameters
from the Define menu
Check the
Retain High Speed Counter
checkbox.
