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IronHorse GSD8 DC Drives User Manual – 1st Ed. Rev. A – 10/15/2019
Parameter Parameter Name
Description
GSD8-
240-5C
All other
GSD8
drives
29
Pulse Accumulation
Limit
This parameter sets the limit for the maximum number of pulses the
drive will accumulate prior to intentionally losing count and therefore
long-term accuracy. The GSD8-240-5C is a pulse-accumulation drive,
able to accurately track a master (in Follower Mode) pulse-by-pulse. Able
to run for days, weeks, or months and remain in sync with a master drive
or process; but this functionality comes at a small cost.
By default, if the main pickup signal is lost and then recovered, the drive
may run at high speed attempting to make-up lost pulses.
Once caught up, the drive returns to normal operation. This change
in speed may be a nuisance and if so, the Pulse Accumulation Limit,
parameter 29, can be lowered to limit the maximum number of pulses
the drive will remember.
This parameter is set from 0 to 9999, where 0 is no accumulation and
9999 is maximum accumulation. As this value approaches zero, the
unit will gradually lose its ability to drive the motor and eventually stop
the motor completely. It may be necessary to increase the value of this
parameter for applications that demand higher long-term accuracy.
Startup Lag
Compensation
Somewhat analogous to a “Min. Speed” control on analog motor speed
controls, this sets a “minimum output” that is applied as soon as the
Target Speed is above Zero RPM. Careful use of this setting can help with
“stiction” (the tendency for motors to require a bit more power to “break
free” when starting from a dead stop). However, values that are too high
will make the motor “creep” or even be unable to attain a desired target
speed. In Follower Mode, this setting can also help the Follower start up
in better “sync” with the Leader.
Signal Input #1 Setup Parameters
30
Signal Input 1 (S1)
(Main Pickup) Display
Reference
This is the number to be displayed when at the user-specified motor
Reference RPM. In Rate Mode, this value represents rate units such as
feet, ounces, or revolutions. In Time Mode, this value represents the
reference time measured in seconds or minutes. If the desired display
is HH:MM, then all values should be entered in minutes. If MM:SS
is desired, then all values should be entered in seconds. In Follower
Mode, this value is the percentage of the master rate in 0.1% units. For
example, 1000 equates to 100%.
31
Signal Input 1 (S1)
Reference RPM
This is the reference RPM at which the Display Reference value should be
displayed. In Rate and Time Modes, this value represents the RPM of the
encoder to which the Display Reference corresponds. In Follower Mode,
this value is not used.
32
Signal Input 1 (S1)
Pulses per Revolution
This is the number of pulses per revolution for the signal input 1 (S1).
The GSD8 supports pickups and encoders from 1 to 9999 pulses per
revolution.
33
Signal Input 1 (S1)
Deadband (Follower
Mode Only)
When in Follower Mode, it is often desirable for the follower to slowly
makeup any small pickup pulse differential between the master and
follower’s position. Depending on the application, it may not be
necessary for the follower to seek the master’s exact pulse position when
the master rate is zero. In these cases, Deadband, parameter 33, can be
set above zero forcing the GSD8-240-5C drive to stop driving the motor
and instead inhibit the drive until the master begins rotating again,
when the follower will automatically make-up the pulse differential as it
starts to rotate. The deadband is disabled by setting it to zero seconds.
Signal Input 1 (S1)
Initial Stall Timeout
When the Target Speed is above zero RPM, this Parameter determines
the maximum time in seconds until the first S1 pickup pulse occurs
before the GSD8 considers itself in a “Stall” Condition. It is not advisable
to set this lower than approximately 10 seconds (a value of 10), or it may
be difficult to achieve startup in a low-speed application. A value of zero
defeats this timeout. (Note: This parameter will only work if the alarm is
set for stall on any of the parameters 50, 51, 52, 70, 71, or 72.)
