GE VersaMax, Руководство пользователя

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13-10 VersaMax® Modules, Power Supplies, and Carriers User's Manual – March 2003 GFK-1504K
13
IC200MDD841
Mixed Module, 24VDC Positive Logic Input 20 Points / Output 12 Point /
(4) High Speed Counter, PWM, or Pulse Train Configurable Points
Type A Counters
The Type A counter is one 16-bit counter that can count up or down. Configurable high
and low limits set the counter’s range.
The counter can either count continuously within its limits, or count to either limit then
stop (one-shot mode). In continuous counting, the Accumulator (see below) wraps when
the count limit is reached and continues counting. For example, if the Count Direction is
up, when the count exceeds the High Limit by 1, the Accumulator value wraps to the Low
Limit. In one-shot mode, the counter stops at the limit.
In the example below, the counter has been configured to count on the low to high
transition of the Pulse input. The Count signal represents an internal signal that indicates
where counting occurs with respect to the pulse input.
Pulse Input
Count
N 2
N 1
N
Accumulator
Value
The Type A counter has an Accumulator register, a Counts per Timebase register, a Strobe
register, high limit, low limit, and ON/OFF Preset values. These are 16-bit signed
numbers. The values selected for the Preload, Accumulator, On Preset, and Off Preset
registers must be within the counter limits. The maximum pulse repetition rate of the
Preload signal and Strobe must be less than 2kHz, and the duty cycle for both must be such
that the signal is high for at least 250 microseconds.
Up or Down Counter (16-bit)
Preload Value
(16-bit)
Strobe Register
(16-bit)
Counts per
Timebase
(16-bit)
Strobe
Count
Pulse
Preload
Accumulator
(16-bit)
On/Off Presets
Output
Preload
/Strobe
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