Danaher Motion Standalone MMC, Руководство по оборудованию

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176 Standalone MMC Hardware Manual
Operation Details
version 15.1
Danaher Motion
Figure A-3: Signals Transmitted by a Quadrature Encoder with Differential
Outputs
The maximum input frequency is 250,000 lines per second, which results in 1,000,000
Feedback Units (FUs) per second.
Figure A-4: Counting Quadrature Pulses
There is a 24-bit up/down counter for each channel. It is incremented or decremented
on each A, B edge. There is also a 24-bit latch associated with each encoder channel.
The module can be programmed so that the counter value is “latched” or stored under
one of these conditions:
• an index pulse from the encoder
• a positive or negative transition of the fast input
• the next index pulse after the required transition of the fast input
Each of the five 24-bit latches has a fast 24 VDC input associated with it. Each input is
optically isolated. This input is intended to receive a signal from a device other than an
encoder. It is typically used for referencing or synchronization purposes.
Fast input characteristics include:
• the detection of a signal occurs faster than it does for the DC inputs in other mod-
ules, due to less filtering. Because of this there is also less noise immunity.
• the response to a fast input signal is independent of ladder scan time. The mod-
ule can be programmed to latch a position count as soon as this input is detected.
ROTATION SPEED
0
A
A
B
B
OUTPUT
B
A
1
2
3
4
5 6
7
8 9
10
11
12
Encoder Count
The module counts positive
transitions at both channel A
and channel B. One quadrature
cycle in this case gives
4 feedback units.