Spectrum Controls SLC 500, User Manual

Page: 29 / 66

Chapter 3: Configuring the 1746sc- CTR4/CTR8 3-5
User’s Manual Pub. 0300181-07 Rev. A
NOTE
In the X4 Quadrature mode, invalid signals are not detected. A broken
input wire, jitter or noise on the input can cause additional counts to be
registered. The modules response to four possible error conditions are
listed below:
•
Input A is active while input B is stuck high: Module will count
down on input A transitions.
•
Input A is active while input B is stuck low: Module will count
down on input A transitions.
•
Input A is stuck high while input B active: Module will count
down on input B transitions.
• Input A is stuck low while input B is active: Module will count
up on input B transitions.
Section 3.5
Modes
There are two methods to gate (start/stop) your counter, hardware and software.
The 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.
External Hardware Gate Lines:
There are four external inputs, one for each pair of input channels, that may be
used to start and stop the counter. Each external gate is pulled low internal to the
module. A low input allows each pair of counter channels to operate. The count
enable line is compatible with 5, 12, and 24 VDC inputs. If pulled high with one
of these inputs the pair of counter channels are disabled.