Emerson Epsilon Eb Series Reference Manual page 54

Host Controller Travel Limits
If the host controller decelerates the drive faster than the Travel Limit Deceleration ramp, the
drive allows the controller to maintain full control of the axis during the deceleration. This
results in no following error build up in the controller and easier recovery.
Vertical Loads in Velocity Mode
In applications with horizontal, counterbalanced or un-counterbalanced vertical loads, the
load will held in position when motion is stopped due to a + or - Travel Limit. The position
will be held until the controller commands motion in the opposite direction of the activated
Travel Limit.
Vertical Loads in Torque Mode
In applications with horizontal or counterbalanced vertical loads, the load will held in position
when motion is stopped due to a + or - Travel Limit. The position will be held until the
controller commands motion in the opposite direction of the activated Travel Limit.
Warning
When an axis is stopped by the upper Travel Limit with a vertical load, the controller must
maintain a torque command at a minimum level to hold the load or the load may drop.
In applications with un-counterbalanced vertical loads, you must be careful not to set the
controller's torque command to zero when the upper Travel limit is activated. Setting the
controllers analog torque command to zero in this situation will command the axis to move
off the limit switch causing the load to drop.
If your controller removes the torque command (zeroes the analog command output) when a
Travel Limit is activated, you have a number of choices to prevent the load from dropping.
All of which require some external logic to determine when the controller can actually take
control again.
• Activate the opposite Travel Limit input function, then release it when the controller is
operational again.
• Activate the Stop input function, then release it when the controller is operational again.
• Apply the axis brake, then release it when the controller is operational again
Pulse Mode
In applications with horizontal, counterbalanced or un-counterbalanced vertical loads, the
load will be held in position when motion is stopped due to a + or - Travel Limit. The position
will be held until the controller commands motion in the opposite direction of the activated
Travel Limit.
When the travel limits are activated, the drive will decelerate at the Travel Limit Deceleration
Ramp and will continue to store all the command pulses received up to ±2
stored pulses need to be cleared out before the axis will move off the Travel Limit. This can
be done if the controller generates command pulses in the direction opposite the activated
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Operational Overview
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