Delta Tau GEO BRICK LV User Manual
Turbo PMAC User Manual
Turbo PMAC Computational Features
237
Compiled PLC Programs 1 – 31
Compiled PLC programs (PLCC programs) 1-31 are executed in background. Each background cycle,
Turbo PMAC will execute one scan (to the end or to an ENDWHILE statement) of all active compiled
background PLC programs, starting from lowest numbered to highest, uninterrupted by any other
background task (although it can be interrupted by higher priority tasks). At power-on/reset, PLCC
programs run after the first PLC program runs.
Turbo PMAC will execute one scan (to the end or to an ENDWHILE statement) of all active compiled
background PLC programs, starting from lowest numbered to highest, uninterrupted by any other
background task (although it can be interrupted by higher priority tasks). At power-on/reset, PLCC
programs run after the first PLC program runs.
Host Command Response
The receipt of a control character from any port is a signal to Turbo PMAC that it must respond to a
command. The most common control character is the carriage return (<CR>), which tells Turbo PMAC
to treat all the preceding alphanumeric characters as a command line. Other control characters have their
own meanings, independent of any alphanumeric characters received. Here Turbo PMAC will take the
appropriate action to the command, or if it is an illegal command, it will report an error to the host.
command. The most common control character is the carriage return (<CR>), which tells Turbo PMAC
to treat all the preceding alphanumeric characters as a command line. Other control characters have their
own meanings, independent of any alphanumeric characters received. Here Turbo PMAC will take the
appropriate action to the command, or if it is an illegal command, it will report an error to the host.
General Housekeeping
Each background cycle, Turbo PMAC performs its housekeeping duties to keep itself properly updated.
The most important of these are the safety limit checks (following error, overtravel limit, fault, watchdog,
etc.); general status updates are done here as well. Although this happens at a low priority, a minimum
frequency is ensured because the watchdog will trip, shutting down the card, if this frequency gets too
low. You can set this required frequency by changing variable I40 from its default value of 0. If I40 is
set to a value greater than 0, this value is the number of servo cycles within which every background
cycle must complete, or the watchdog timer will trip. (If I40 is set to 0, this number is 4096 servo cycles.)
The following diagram shows a time-line example of Turbo PMAC’s multi-tasking, focusing on the
servo, real-time interrupt, and background tasks.
The most important of these are the safety limit checks (following error, overtravel limit, fault, watchdog,
etc.); general status updates are done here as well. Although this happens at a low priority, a minimum
frequency is ensured because the watchdog will trip, shutting down the card, if this frequency gets too
low. You can set this required frequency by changing variable I40 from its default value of 0. If I40 is
set to a value greater than 0, this value is the number of servo cycles within which every background
cycle must complete, or the watchdog timer will trip. (If I40 is set to 0, this number is 4096 servo cycles.)
The following diagram shows a time-line example of Turbo PMAC’s multi-tasking, focusing on the
servo, real-time interrupt, and background tasks.
Comm - Communications Line Processing
- Servo Interrupt
RTI - Real Time Interrupt Task
* - Start of RTI
- Servo Interrupt
RTI - Real Time Interrupt Task
* - Start of RTI
CT
#1
#2
#3
#4
PLC 0
PLC 1...
Servo
RTI
Background
CT
#1
#2
#3
#4
PLC 1 (cont.)
PLC 2...
Servo
Background
CT
#1
#2
#3
#4
PLC 2 (cont.)
PLC 3...
Servo
CT
#1
#2
#3
#4
PLC 0
Move Planning ...
Servo
RTI
CT
#1
#2
#3
#4
Move Planning (cont)
PLC 3 (cont) ...
Servo
RTI
Background
CT
#1
#2
#3
#4
PLC 3 (cont)
PLC 1 ...
Servo
Background
CT
#1
#2
#3
#4
PLC 0
PLC 1 (cont) ...
Servo
RTI
CT
#1
#2
#3
#4
Servo
Background
HK
HK Comm
HK
PLC 1 (cont)
Comm
HK
*
*
*
CT - Conversion Table
# n - Motor n Servo Update
HK - Housekeeping
# n - Motor n Servo Update
HK - Housekeeping
PMAC Multitasking Example
Background