Embedding VME and IndustryPacks helps with control

When Data Respons, a Norwegian system integrator, was faced with a factory automation task, it used a modular computer architecture based on Motorola IndustryPack modules and VME boards. The task was to feed sheets of cardboard (blanks) from a stack onto a conveyor. This transfers them into a machine which folds and glues them into […]

When Data Respons, a Norwegian system integrator, was faced with a factory automation task, it used a modular computer architecture based on Motorola IndustryPack modules and VME boards.

The task was to feed sheets of cardboard (blanks) from a stack onto a conveyor. This transfers them into a machine which folds and glues them into cartons. Belt speed had to be 10m/sec, and distance between them, 10-20 mm – a time interval of 1msec.

Data Respons used three, individually controllable servo motors. Two optical analogue sensors were selected to measure the distance between blanks, and digital sensors and actuators to control sub-systems.

Blanks are 300mm long, and have to be transferred every 32msec, so this determined the servo motor speed regulation period. And the system had to handle positional variations of up to 20mm, compensation again having to be handled by the servos during the time window.

A VMEbus system was selected because VME boards were available with the requisite performance. Data Respons chose an MVME162 board, incorporating a 25MHz 68040, 4Mb DRAM, 512kb SRAM and four IndustryPack sites as the processor. IndustryPack mezzanine modules were used to add digital I/O, analogue I/O and servo motor control.

The result was a very compact embedded solution. System timings were generated using hardware on the MVME162 board and interrupts. Data Respons used the pSOS+ real time OS.

Data Respons says that the VME processor with IndustryPacks for custom I/O was a very cost effective approach. It was easy to understand and to implement – most importantly, without any hardware customising.

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