Reference Manual

PMAC 2 Software Reference

PMAC I-Variable Specification 165

I1021 Lookahead State Control {Option 6L Firmware Only}

Range

0 – 15

Units

none

Default

Remarks

I1021 permits direct control of the state of lookahead execution, without going through

PMAC’s background command interpreter. This is useful for applications such as wire

EDM, which can require very quick stops and reversals.

• Setting I1021 to 4 is the equivalent of issuing the \ quick-stop command

• Setting I1021 to 7 is the equivalent of issuing the < back-up command

• Setting I1021 to 6 is the equivalent of resuming forward motion with the > resume

forward command.

If you are monitoring I1021 at other times, you will see that the “4’s” bit is cleared after

the command has been processed. Therefore, you will see the following values:

• I1021 = 0 when stopped with a quick-stop command

• I1021 = 3 when running reversed in lookahead

• I1021 = 2 when running forward in lookahead

Note:

In preliminary versions of the special PMAC lookahead firmware,

I1021 served a different function. That variable value is now a

constant value (3) set by the firmware.