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ADDITIONAL PCM-5 PROGRAMMING
PARAMETERS
Five additional questions can be answered when using a PCM-5 with a drive.
Figure 71
PCM-5 Drive Parameters
LEAD AXIS
The default condition (ENC) means that the SCS-2 will generate the sync pulses. Selecting
(DRV) means that the lead axis is a digital drive.
SYNC RATIO
SYNC RATIO establishes the relationship of the follower axis to the lead axis. The relationship
to establish is: How many turns of the follower axis equal one turn of the lead? The range is
programmable from (.125 to 20) turns. Since, in a digital system, counting is based on bits with
no way to resolve numbers between these bits, infinite resolution is not possible. PCX will
convert, if required, your entry to the closest possible ratio. Since the standard SCS-2 encoder
produces 4000 counts per revolution, and a digital drive is based on 12 bits binary (4096) then
4000 or 4096, become constants in the calculation. The digital drive through serial control,
needs a numeric value in a range of 200 – 32,000. This is stored as "SR1". The relationship of
these terms is
N
SR1
= TURNS OF FOLLOWER AXIS TO TURNS OF LEAD AXIS
WHERE N IS 4000 IF LEAD AXIS IS AN ENCODER
WHERE N IS 4096 IF LEAD AXIS IS A DIGITAL DRIVE
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