Specifications

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3401 Manual
Point I/O Stepper Module
Revision 2.0
Find Home +/(CW), Find Home -/(CCW)
There are two homing options available. They are,
1. Home Limit Switch Only
2. Home Limit Switch with a backplane Home Proximity bit.
When the homing operation is complete, the 3401 will set the At Home input bit, and then resets the
current position to zero.
The Find Home commands require that the 3401 module has been configured to allow homing in the
specified direction. The 3401 will not accept a Find Home +/(CW) command when it has not been
configured to allow CW homing (Configuration word 0, bit 4). Likewise, it will not accept a Find Home
-/(CCW) command when it has not been configured to allow CCW homing (Configuration word 0, bit 5).
If either of these operations are attempted, the HOME INVALID Error bit will be set.
S-Curve acceleration profiles are not allowed during a homing operation. Initiating a home operation
with S curve accelerations will cause a command error to be generated.
If the Limit Input is reached during a homing operation, and if the direction of homing matches the
configuration of the Limit Input (CW Over Travel Limit Switch and a CW homing operation), then the
module will stop outputting pulses (essentially an emergency stop), wait for two seconds, reverse
direction, and start searching for the appropriate homing signal again. It is important not to have the
velocity set to high during a homing operation. The sudden stop and change in direction at high speeds
may cause the motor to lock up.
If the opposite Limit Input is reached during a homing operation (CCW Over travel Limit Switch and a
CW homing operation or the CW Over travel Limit Switch and a CCW homing operation), then the
module will stop outputting pulses and set the Input Error, Home Invalid, and the Position Invalid Error
bits.
It is possible to home off of an active Over Travel Limit Switch. For example, you can perform a CW
home operation if the CCW Over Travel Limit Switch is active.
The following diagrams illustrate the different homing options.
Home Limit Switch Only
1. Accelerates to
programmed speed
2. Runs at the
programmed speed
3. Detects the Home Limit
Switch
4. Decelerates to stop
and waits 2 seconds.
7. Returns to the Home Limit
Switch at the starting speed
5. Accelerates to the programmed
speed opposite to the requested
direction
6. Decelerates when the Home
Limit Switch goes On then
Off. Waits 2 seconds