Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
350
Synchronizing Turbo PMAC to External Events
For instance, if the table started with eight 1/T entries (using I8000 – I8007), and the time-base entry
followed using I8008 and I8009, the resulting time base value would be in the X-register accompanying
I8009 (address X:$350A). To use this value as the time base for Coordinate System 1, issue the
command I5193=$350A (specifying the address directly), or I5193=@I8009 (specifying the address
through the location of the I-variable). Both commands yield the same result.
followed using I8008 and I8009, the resulting time base value would be in the X-register accompanying
I8009 (address X:$350A). To use this value as the time base for Coordinate System 1, issue the
command I5193=$350A (specifying the address directly), or I5193=@I8009 (specifying the address
through the location of the I-variable). Both commands yield the same result.
Once this I-variable has been set up, all motors assigned to this coordinate system will be under the
control of the external frequency, in programmed and non-programmed moves.
control of the external frequency, in programmed and non-programmed moves.
I-variable Isx94 controls the maximum rate of change of the time-base value for Coordinate System x.
When commanding the time-base value from the host (with a %n command), this value should be fairly
low to produce a nice slewing to the new commanded value. However, to keep synchronized to an
external signal as time-base source, this value should be set as high as possible (maximum value is
8,388,607) so the time base can always slew as fast as the signal. Setting the value low can improve
following smoothness at the cost of some ‘slip’ in the following. If the Isx94 limit is ever used in external
time base, position synchronization to the master is lost.
When commanding the time-base value from the host (with a %n command), this value should be fairly
low to produce a nice slewing to the new commanded value. However, to keep synchronized to an
external signal as time-base source, this value should be set as high as possible (maximum value is
8,388,607) so the time base can always slew as fast as the signal. Setting the value low can improve
following smoothness at the cost of some ‘slip’ in the following. If the Isx94 limit is ever used in external
time base, position synchronization to the master is lost.
Step 5: Writing the Program
When writing the program that is to be under external time-base control, simply write it as if the input
signal were always at the real-time frequency. When run, the program will execute at a rate proportional
to the input frequency. There is full floating-point resolution on the move times and feedrates that are
specify.
signal were always at the real-time frequency. When run, the program will execute at a rate proportional
to the input frequency. There is full floating-point resolution on the move times and feedrates that are
specify.
Remember that DWELL commands always execute in real time, regardless of the input frequency. To
have pauses in the program that are proportional to an input frequency, use the DELAY command, not
DWELL.
have pauses in the program that are proportional to an input frequency, use the DELAY command, not
DWELL.
Time-Base Example
If there is a web of material moving at a nominal speed of 50 inches per second, there is a quadrature
encoder on the web that gives 500 lines per inch. There is a crosscutting axis under Turbo PMAC
control. When the web is moving at nominal speed, make a cutting move in 0.75 seconds and be ready to
start another move 2.50 seconds later. The web encoder is attached to Servo IC 2 Encoder 4 input lines.
encoder on the web that gives 500 lines per inch. There is a crosscutting axis under Turbo PMAC
control. When the web is moving at nominal speed, make a cutting move in 0.75 seconds and be ready to
start another move 2.50 seconds later. The web encoder is attached to Servo IC 2 Encoder 4 input lines.
Step 1: Signal Decoding
Since the web encoder is Servo IC 2 Encoder 4, I7240 controls the decoding. For maximum resolution,
set I7240 to 3 or 7 for x4 decode. Try 3 first. Looking in the list of suggested M-variables in the manual,
notice that the encoder position M-variable for this encoder is M401 for a UMAC or M1201 for other
types of Turbo PMAC. Make the definition for M401 or M1201 and query its value repeatedly (probably
using the Executive program Watch window) while turning the web encoder in the direction it will be
going in the application. If the value increases as the encoder is turned, I7240 is set properly. If it
decreases, change I7240 to 7. (If it does not change, check the connections.)
set I7240 to 3 or 7 for x4 decode. Try 3 first. Looking in the list of suggested M-variables in the manual,
notice that the encoder position M-variable for this encoder is M401 for a UMAC or M1201 for other
types of Turbo PMAC. Make the definition for M401 or M1201 and query its value repeatedly (probably
using the Executive program Watch window) while turning the web encoder in the direction it will be
going in the application. If the value increases as the encoder is turned, I7240 is set properly. If it
decreases, change I7240 to 7. (If it does not change, check the connections.)
Step 2: Interpolation
Next, look at the current setup of the encoder conversion table. Make sure the encoder is processed with
a 1/T conversion. The easiest way to do this is through the Configuration menu of the PMAC Executive
program. If this is not available, look at the I8000+ variables directly. Issue a command such as
I8000..8009 and get back something like this:
a 1/T conversion. The easiest way to do this is through the Configuration menu of the PMAC Executive
program. If this is not available, look at the I8000+ variables directly. Issue a command such as
I8000..8009 and get back something like this:
$078200
$078208
$078210
$078218
$078300
$078308
$078310