Reference Manual

PMAC 2 Software Reference

PMAC I-Variable Specification 63

Note:

When changing this parameter, make sure the motor is killed

(disabled). Otherwise, a sudden jump will occur, because the

internal position registers will have changed. This means that this

parameter should not be changed in the middle of an application. If

a real-time change in the position-following “gear ratio” is desired,

Ix07 should be changed.

In most practical cases, Ix08 should not be set above 1000 because higher values can make

the servo filter saturate too easily. If Ix08 is changed, Ix30 should be changed inversely to

keep the same servo performance (e.g. if Ix08 is doubled, Ix30 should be halved).

See Also

Position Following (Synchronizing PMAC to External Events)

I-variables Ix05, Ix06, Ix07, Ix09, Ix30

Ix09 Motor x Velocity Loop Scale Factor

Range

0 .. 8,388,607

Units

none

Default

Remarks

Ix09 controls how the encoder counter used to close the velocity servo loop gets extended

into the full-length register. For most purposes, this is transparent to the user and does not

need to be changed from the default. This parameter should not be changed in the middle

of an application, because it scales many internal values. If the same sensor is used to

close both the position and velocity loops (Ix03), Ix09 should be set equal to Ix08.

If different sensors are used, Ix09 should be set such that the ratio of Ix09 to Ix08 is

inversely proportional to the ratio of the velocity sensor resolution (at the load) to the

position sensor resolution.

Example

If a 5000 line/inch (20,000 cts/in) linear encoder is used for position feedback, and a 500

line/rev (2000 cts/rev) rotary encoder is used for velocity loop feedback, and there is a 5-

pitch screw, the effective resolution of the velocity encoder is 10,000 cts/in (2000x5), half

of the position sensor resolution, so Ix09 should be set to twice Ix08.

If the value computed this way for Ix09 does not come to an integer, use the nearest integer

value.