Delta Tau GEO MACRO DRIVE User Manual download pdf (Page 116)

Geo MACRO Drive User Manual

104 Setting Up Discrete Inputs and Outputs

MS0,MI926=1010 ; Set back end compare in B

MS0,MI923=0 ; No auto-increment

MS0,MI929=0 ; Prepare initial value of 0

MS0,MI928=1 ; Enable direct write (resets immediately to zero)

{Command to start the move}

Setting up for Multiple Pulse Outputs

By using the auto-increment feature, it is possible to create multiple compare pulses with a single software setup

operation. When the auto-increment register is a non-zero value, its value is added to or subtracted from one

compare register’s value automatically when the other compare value is matched. PMAC keeps track of the

direction of incrementing, so only positive values should be used in the auto-increment register, even if the

encoder will be counting in the negative direction.

The setup for multiple pulses is like the setup for a single pulse, except that a non-zero value must be entered

into the auto-increment register and the value entered for the back edge must be that of the first back edge minus

the auto-increment if the move will be positive or that of the first back edge plus the auto-increment value if the

move will be negative.

In other words, the starting values to the two compare registers must “bracket” the starting position. When either

compare value is matched by the encoder counter, the other compare value is incremented in the direction of

movement.

Starting Position

Auto-Increment

Example: Starting with the above example, the compare output should be between 1000 (A

) and 1010 (B

)

counts, but add an auto-increment value of 2000 counts with a starting position of about 100 counts. The

program code to start the sequence could be:

MS0,MI925=2000 ; Auto-increment of 2000 encoder counts

MS0,MI926=1000 ; First front edge (A0) at 1000 counts

MS0,MI923=(1010-1000) ;[1010-MS0,MI926]First back edge (B1) at 1010 counts

MS0,MI929=0 ; Prepare initial value of 0

MS0,MI928=1 ; Enable direct write (resets immediately to zero)

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Delta Tau GEO MACRO DRIVE User Manual Page 116