Time Triggered Networks
- distributed SCADA
Combining the use of PXI RT operating systems and a National Instruments
time triggered network, this software was able to distribute the hydraulic
power supplies from the hydraulic test bench.
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noise reduction
The end user is able to situate the noisy power packs in a sound proofed room
up to 50M away from the test area with no loss or delay in signal.
-
simple cabling
The time triggered network requires only one CAT5 Ethernet cable running to
each node making electrical installation of this system much more straightforward.
-
Real time response
Using the Time Triggered Network as a base, and with software developed by Amfax,
this system is able to guarantee that any one processor node on the network is
aware of the I/O state of all other nodes every 50ms. This means that any
developing hydraulic condition on the test bench can be reacted to instantly by the
power supply, making a closed and distributed PID loop possible (see below)
PID pump control - constant pressure or flow
The pump systems used on this rig were only designed to offer constant pressure
but the test specifications demanded constant flow.
We were able to use PID technology, strict loop timing from RT to allow the customer
to use the pumps for BOTH constant pressure and constant flow.
Swash plate excitation - enhanced pump performance
A new requirement for tighter pump tolerances pushed the
pumps beyond their listed performance
We were able to use the strict loop timing regime offered by RT and National
Instruments analogue voltage output to modulate the control voltage to the pumps
using adaptive square wave excitation.
This improved the performance of the pumps accuracy above and beyond that listed
by the manufacturer, allowing our customer to meet their test requirements without
having to replace the hydraulic pumps at significant cost.
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