Rockwell Automation 57C421B Pulsetach Input Module/DCS 5000/AutoMax - Manual (Page 11)

2Ć3
2.2 Electrical Description
The module contains a pulsetachĆtoĆdigital converter that supplies
data to a 24Ćbit up/down counter. See figure 2.2. The counter counts
up as it follows the pulses received from the pulsetach turning in the
forward direction. It counts down as it follows the pulses received
from the pulsetach in the reverse direction.
Counter
Value
Time
Forward
Reverse
Stop
Forward
Stop
Pulsetach
direction
Figure 2.2 Ć Relationship of Pulsetach Direction to Counter Value
The counter data is latched (i.e., frozen in time) and transferred to
latch registers at userĆspecified intervals. The application program
accesses the counter data through the latch registers.
The module also contains an internal 200 kHz clock that can be
used for timing operations.
The module's pulsetach input circuitry is shown in figure 2.3.