1. Introduction to Multi-Tasking

2. Terminology Program: A BASIC or IEC program
Task: IEC task containing one or more programs
Process: Processing slot that runs a Task or BASIC program
Kernel: Processing of the servo and motion firmware

3. Controller type determines the max number of processes
Comparison table
Controller type determines the max number of processes
Controller # Processes Axes
MC ½ / 3 (16 in s/w)
MC ½ / 5 (16 in s/w)
MC / 64 (64 in s/w)
MC664-X / 128 (128 in s/w)
Euro (16 in S/W)
Euro (16 in S/W)

4. Multi-Tasking: Benefits
Division of Tasks
Smaller, dedicated programs (processes) can be written to handle specific functions of the machine.
Concurrency
Each process acts like a virtual controller and operates independently of the others.
Simplified Error
Handling
A simple process can be dedicated to error trapping with no overhead in the main tasks.
Command Line
The command line / Motion Perfect Link is always available, even when programs are running.

5. Multi-Tasking: Division of tasks
STARTUP:
Initialise Axis Parameters and User Memory
(Generated by MotionPerfect)
MAIN:
Error Handler and Safety Interlocks
MAIN
(Error Handler)
STARTUP
(Axis Params
/Variables)
Runs Once
HOMING:
Axis Datuming
Continuous Loop
MOTION1:
Main Motion Loop
HOMING
MOTION1
LADDER
IEC
MOTION2
MOTION2:
Alternative Motion Loop

6. Multi-Tasking: Servo Period
1 msec
Servos & Motion
System
User
User
User
Processor Interrupts
Each interrupt causes a process switch.
All data from running program and the line number are stored
Data for next process slot is retrieved
Programs run from where they left off last time
As more programs are run, they appear to slow down.

7. Multi-Tasking: Servo Period
1 msec
Servos & Motion
System
User
User
User
500 usec
500 usec
Servos & Motion
System
User
Servos & Motion
User
User
250 usec
250 usec
250 usec
250 usec
Servos & Motion
Sys
Servos & Motion
User
Servos & Motion
User
Servos & Motion
User

8. Multi-Tasking: Servo Period
1 msec
Servos & Motion
System
User
User
User
SYSTEM_LOAD
(% of processing time)
More axes running.
Servo and Motion processing takes longer.
Less time shared between multi-tasking processes.

9. Multi-Tasking: Program priority

10. Multi-Tasking: Program priority

11. Multi-Tasking: Program priority

12. Multi-Tasking: Program priority

13. * Expert tip ! See process % in Terminal #0
>>PROCESS Process Type Status Name Line hhhh:mm:ss.ms [CPU %] Slow Pause STARTUP :00: [ 0.00%] Fast Run USER_PROGRAM :00: [30.57%] Fast Run USER_PROGRAM :00: [33.20%] SYS Run Command Line :00: [ 0.06%] SYS Run Protocol Scheduler :00: [ 4.89%] SYS Run MPE :00: [ 4.89%] SYS Suspend CAN Server :00: [ 0.00%] SYS Run TCP/IP Server :00: [ 4.90%] SYS Run ECAT async :00: [ 4.89%] SYS Sleep[ 0] Data Backup :00: [ 0.98%] SYS Sleep[ 9] Directory Backup :00: [ 0.00%] SYS Run Display Manager :00: [ 1.75%] KERNEL SYS Run Motion/Housekeeping :00: [13.86%] >>

14. Kernel: Processing motion
1 msec
Kernel
System
User
User
User
SYSTEM_LOAD
(% of processing time)
Kernel runs closed loop and motion profile generation.
System slot runs communications.
User slots run BASIC and IEC programs.
?SYSTEM_LOAD >>

15. Multi-tasking and Motion
Servo loops and velocity profile
Move type
Next move type
Motion Buffers and Alarms

16. Multi-tasking and Motion
BASIC Multi-Tasking
Velocity Profile Unit
Servo Control
Runs BASIC programs
SPEED=1200
ACCEL=3400
MOVE(340)
WAIT IDLE
PMOVE
Generates motion profile points.
NTYPE … MTYPE
DPOS
DEMAND_SPEED
Calculates Servo control values for all axes.
MPOS…ENCODER
Servo control
algorithm
DAC_OUT
Task switch 3 times per msec
No guaranteed loop times.
Processed once per servo period
[Deterministic]
Processed once per servo period
[Deterministic]