CONTREX MLP-Drive - Manual (Page 88)

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Zero Error Loop
The MLP-Drive has the ability to eliminate any long term speed error in the follower
mode. This is equivalent to maintaining a follower position relative to the lead. This is
accomplished by keeping track of all the scaled lead and follower sensor pulses, and
then adjusting the setpoint to the speed control loop to eliminate any error.
The following control parameters are used by the MLP-Drive for zero error control:
Lag Pulse Limit (CP-18)
The Lag Pulse Limit sets a maximum pulse error for the lagging (fol-
lower is behind in position) feedback pulses that are maintained in the
zero error loop. It may not always be desirable to recover all of the
position error lag.
Lead Pulse Limit (CP-19)
The Lead Pulse Limit sets a maximum pulse error for the leading
(follower is ahead in position) feedback pulses that are maintained in
the zero error loop. It may not always be desirable to recover all of the
position error lead.
Recovery Multiplier (CP-29)
The Recovery Multiplier determines the rate at which the pulse error
(position) is reduced to zero. This parameter multipied by the pulse
error count is the amount by which the speed setpoint is adjusted every
100 milliseconds.
Table 3-41 Default Zero Error Loop Control Parameters
CP Parameter Name Parameter Value
CP-18 Lag Pulse Limit 0
CP-19 Lead Pulse Limit 0
CP-29 Recovery Multiplier 0