User's Manual

Geo MACRO Drive User Manual
142 Geo Macro Drive MI-Variable Reference
Primary Channel Node-Specific Gate Array MI-variables
MI-variables MI910 through MI929 on the Geo MACRO Station control the hardware setup of the
hardware interface channel on the station associated a Geo MACRO Node. The matching of hardware
interface channels to Geo MACRO Nodes is determined by the setting of the Station Number via the
MACRO ring method.
These variables are accessed using the “MS{node}” station auxiliary read and write commands. The
number immediately after the “MS” specifies the node number, and therefore the channel number mapped
to that node by the MACRO ring method.
MS{node},MI910 Primary Encoder/Timer n Decode Control
Range: 0 - 15
Units: None
Default: 7
MI910 controls how the input signal for the encoder mapped to the specified node is decoded into counts.
As such, this defines the sign and magnitude of a “count”. The following settings may be used to decode
an input signal.
0: Pulse and direction CW
1: x1 quadrature decode CW
2: x2 quadrature decode CW
3: x4 quadrature decode CW
4: Pulse and direction CCW
5: x1 quadrature decode CCW
6: x2 quadrature decode CCW
7: x4 quadrature decode CCW
8: Internal pulse and direction
9: Not used
10: Not used
11: x6 hall format decode CW
12: MLDT pulse timer control ;( internal pulse resets timer; external pulse latches timer)
13: Not used
14: Not used
15: x6 hall format decode CCW
In any of the quadrature decode modes; PMAC is expecting two input waveforms on CHAn and CHBn,
each with approximately 50% duty cycle, and approximately one-quarter of a cycle out of phase with
each other. “Times-one” (x1) decode provides one count per cycle; x2 provides two counts per cycle; and
x4 provides four counts per cycle. The vast majority of users select x4 decode to get maximum
resolution.
The “clockwise” (CW) and “counterclockwise” (CCW) options simply control which direction counts up.
If you get the wrong direction sense, simply change to the other option (e.g. from 7 to 3 or vice versa).
Note:
If you change the direction sense of an encoder with a properly working servo
without also changing the direction sense of the output, you can get destabilizing
positive feedback to your servo and a dangerous runaway condition.
In the pulse-and-direction decode mode, PMAC is expecting the pulse train on CHAn, and the direction