Rockwell Automation 1746-HSCE2 Multi-Channel High Speed Counter Module - Manual (Page 26)

Publication 1746-UM002B-EN-P - August 2004
2-6 Module Operation
Gate/Preset Modes A counter’s gate/preset mode determines what, if any, gating is
applied to the counter and what, if any, conditions will preset the
counter to the preset value. The Z inputs are the only inputs used for
gating or presetting. The six gate/preset modes are described below.
No Preset
The counter is not preset under any conditions. The Z inputs are not
used.
Soft Preset Only
The counter is preset when the matching preset bit in the SLC 500
output image table experiences a positive transition, but not in
response to the Z input.
Store/Continue
The count value is captured when the module detects an
inactive-to-active transition on the Z input of the counter. This stored
value is made available to the backplane. A stored status bit in the
input image table is set to signal the processor that a new value is
available. This bit is active until the capture value is read by the
processor. Therefore, it is on for a maximum of 10 ms in Class 1, and
a maximum of one scan or 10 ms, whichever is shorter, in Class 4. If a
second capture event occurs before the first is read, the first value is
lost. The count and rate values are not affected by a store event.
TIP
The soft preset bit operates in all the gate/preset
modes except No Preset.
store, continue
counting