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104 • Chapter 6 Programming Motion DMC-3425
Command Summary - Homing Operation
COMMAND DESCRIPTION
FE ABCD Find Edge Routine. This routine monitors the Home Input
FI ABCD Find Index Routine - This routine monitors the Index Input
HM ABCD Home Routine - This routine combines FE and FI as Described Above
SC ABCD Stop Code
TS ABCD Tell Status of Switches and Inputs
Operand Summary - Homing Operation
OPERAND DESCRIPTION
_HMn Contains the value of the state of the Home Input
_SCn Contains stop code
_TSn Contains status of switches and inputs
High Speed Position Capture (Latch)
Often it is desirable to capture the position precisely for registration applications. The DMC-3425
provides a position latch feature. This feature allows the position of the encoders of A or B axis to be
captured when the latch input changes state. This function can be setup such that the position is
captured when the latch input goes high or low. The inputs on these controllers are TTL. Latch time
latency on a high or low going signal is less than 1μsec. Each axis has one general input associated to
the axis for position capture:
Input Function
IN1 A Axis Latch
IN2 B Axis Latch
The DMC-3425 software commands, AL and RL, are used to arm the latch and report the latched
position. The steps to use the latch are as follows:
1. Give the AL AB command to arm the latch.
2. Test to see if the latch has occurred (Input goes low) by testing the operand, _ALA or
_ALB. Example, V1=_ALA returns the state of the A latch into V1. V1 is 1 if the latch
has not occurred.
3. After the latch has occurred, read the captured position with the command RL AB or RL
AB command or monitor the value of the operands _RLA and _RLB.
NOTE: The latch must be re-armed after each latching event.