Reference Manual

ManualsBrandsDelta Tau ManualsControllersDelta Tau PMAC VME

141

142

143

144

145

146

147

148

149

150

PMAC 2 Software Reference

132 PMAC I-Variable Specifiation

Example

To set a PWM frequency of 7.5 kHz and therefore a MaxPhase clock frequency of 15 kHz:

I900 = (117,964.8 kHz / [4*7.5 kHz]) - 1 = 3931

See Also

I901, I902, I905, I906, I992

I901 Phase Clock Frequency Control {PMAC2 only}

Range

0 .. 15

Units

PHASE Clock Frequency = MaxPhase Frequency / (I901+1)

Default

PHASE Clock Frequency = 9.0346 kHz / 1 = 9.0346 kHz

(with default value of I900)

Remarks

I901, in conjunction with I900, determines the frequency of the PHASE clock on PMAC2

(except for PMAC2 Ultralites, which use I992 and I997 for this). Each cycle of the

PHASE clock, motor phase commutation and digital current-loop algorithms are

performed for specified motors.

Specifically, I901 controls how many times the PHASE clock frequency is divided down

from the “maximum phase” clock, whose frequency is set by I900. The PHASE clock

frequency is equal to the “maximum phase” clock frequency divided by (I901+1). I901

has a range of 0 to 15, so the frequency division can be by a factor of 1 to 16. The

equation for I901 is:

)kHz(PhaseFreq

)kHz(eqMaxPhaseFr

901I −=

The ratio of MaxPhase Freq. to PHASE Clock Freq. must be an integer.

Note:

If jumper E1 is ON, PMAC2 gets its PHASE clock signal externally

from a serial-port input, and I901 is not used.

Note:

If the phase clock frequency is set too high, lower priority tasks

such as communications can be starved for time. If the background

tasks are completely starved, the watchdog timer will trip, shutting

down the board. If a normal reset of the board does not re-establish

a state where the watchdog timer has not tripped and

communications works well, it will be necessary to re-initialize the

board by powering up with the E3 re-initialization jumper on. This

restores default settings, so communication is possible, and I900

and I901 can be set to supportable values.

Example

With a 20 kHz MaxPhase Clock frequency established by I900, and a desired 6.67 kHz

PHASE clock frequency, the ratio between MaxPhase and PHASE is 3:

I901 = (20 / 6.67) - 1 = 3 -1 = 2