Reference Manual

PMAC 2 Software Reference
126 PMAC I-Variable Specifiation
Ix97 (Reserved for Future Use)
Ix98 Coordinate System x Maximum Feedrate
Range
Non-negative floating-point
Units
User axis length/angle units per Ix90 milliseconds
Default
0
Remarks
Ix98 permits a maximum feedrate to be set for a coordinate system, preventing a program
from accidentally exceeding a specified value. If Ix98 is greater than 0, PMAC will
compare each commanded vector feedrate value from an F command in a motion program
to Ix98. If the commanded feedrate is greater than Ix98, it will use Ix98 instead.
If Ix98 is set to 0, PMAC will not check the programmed feedrate value against a limit.
Ix99 (Reserved for Future Use)
PMAC(1) Encoder/Flag Setup I-Variables
One PMAC can have up to 16 incremental encoder channels – four per gate array IC. Each encoder and
its related flags and registers are set up using (up to) 5 I-variables. The encoders and their flags are
numbered 1 to 16, matching the numbers of their pinouts (e.g. CHA1, CHB1, and CHC1 belong to
encoder 1.) The encoder I-variables are assigned to the different encoders as follows:
I900 - I904 – Encoder 1
I905 - I909 – Encoder 2
I910 - I914 – Encoder 3
I915 - I919 – Encoder 4
...
I970 - I974 – Encoder 15
I975 - I979 – Encoder 16
An encoder is assigned to a motor for position, velocity (feedback), handwheel (master), or feedpot
(frequency control) by using the appropriate motor I-variables (see above).
I900, I905, ..., I975 Encoder n Decode Control “Encoder I-Variable 0” {PMAC(1) Only}
Range
0 .. 15
Units
none
Default
7
Remarks
WARNING:
Changing the direction sense of the encoder decode for a motor that
is servoing properly will result in unstable positive feedback and a
dangerous runaway condition in the absence of other changes (for
motors not commutated by PMAC from the same encoder). The
output polarity must be changed as well to re-establish polarity
match for stable negative feedback.
This parameter controls how the input signal for Encoder n is decoded into counts. As
such, this defines the sign and magnitude of a count.