Delta Tau GEO MACRO DRIVE User Manual download pdf (Page 115)

Geo MACRO Drive User and Reference Manual

Setting Up Discrete Inputs and Outputs 103

Setting up Position Compare (EQU) Outputs

The position-compare feature is a dedicated hardware circuit in the Servo ASICs that creates an output

pulse when an exact encoder position is reached. Because it uses actual position, servo following errors

do not affect the accuracy. Because it is a hardware feature, there are no software delays in generating the

pulse.

Because it is a hardware function, it can operate asynchronously from the programmed motion sequence.

For this reason, it is often managed from a PLC program if it needs to be updated more than once per

programmed move.

The position-compare function works with the raw encoder position, which is referenced to the power-

up/reset position because the counter is forced to zero at that time. In general, this is different from the

motor zero position (home) or the axis programming zero position and it will be different every time the

Turbo PMAC is powered up or reset.

To monitor the status of the actual position compare output point an M-Variable definition to bit 9 of the flag

copy register (Ixx25). Using this method, the IO copy register does not need to be set up to verify the operation

of the compare outputs. These data bits are updated every ring cycle.

Turbo Ultralite

M152->X:$003440,9

M252->X:$003441,9

M352->X:$003444,9

M452->X:$003445,9

M552->X:$003448,9

M652->X:$003449,9

M752->X:$00344C,9

M852->X:$00344D,9

The Position Compare Outputs (EQU Outputs) are set up using the following MACRO Node registers:

MS{node},MI912 Encoder n Capture Control

MS{node},MI923 Compare Auto-Increment Value

MS{node},MI925 Compare A Position Value

MS{node},MI926 Compare B Position Value

MS{node},MI928 Compare-State Write Enable

MS{node},MI929 Compare-Output Initial State

For Geo MACRO drives, only MS{node},MI920 was set to point to the raw ENC 24-bit counter position

Setting up for a Single Pulse Output

If only a single compare pulse is desired (not using the auto-increment feature), the following steps should

be taken:

1. Write the encoder value at the front edge into the Compare A register.

2. Write the encoder value at the back edge into the Compare B register.

3. Set the Auto-Increment register to zero.

4. Set the initial state with the direct-write feature.

5. Write a value to the initial state bit.

6. Write a 1 to the direct-write enable bit (this is self-clearing to 0).

7. Start the move that will cause the compare function.

Example: For axis 1 using node 0, with the axis sitting still at about encoder position 100 and a 1 value of

position compare desired between encoder positions 1000 and 1010, the following code could be used:

MS0,MI925=1000 ; Set front end compare in A

1 2 ... 110 111 112 113 114 115 116 117 118 119 120 ... 204 205

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Delta Tau GEO MACRO DRIVE User Manual Page 115

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