Omega-vehicle-security OMP-MODL Manuel d'utilisateur télécharger pdf (Page 274)

11.. . APPENDIX C: HYPERWARE FILE LISTING

USING THE OMP-MODL11-112

High Speed Thermocouple Application:

In some applications, maximum speed of thermocouple measurement is desired.

The Thermocouple icon is one of the slowest to process in a Program Net due to the

intensive math associated with each sample. A Cold Junction Compensation

reading is required as well as the thermocouple reading, then the two are combined

through curve approximating polynomials... heavy math for the OMP-MODL.

A method to improve on the throughput rate of thermocouple inputs exists. If the

thermocouple inputs are read as mV signals (which are processsed very quickly) and

the CJC is read as a resistance (which is lots faster than temperature), the net will

process many times faster. The mV readings from the Thermocouple icon and the

resistance reading from the CJC icon are then merged in a Post-Processing Net and

the results (in degrees) are put into a destination *.HLD file for plotting.

The following Program Net represents an application of this method of high speed

thermocouple temperature data collection. Temperature rise data on components

within an automobile brake is desired. Thermocouples are installed and connected

to OMP-MODL input channels configured as mV inputs. The CJC input is sent to

memory in units of OHMS.

A unique triggering scheme is implemented with the Event icon and three Sample

Rate Clocks. One Sample Rate Clock causes the Event icon to sample the status of

a switch connected to the brake pedal every 10mS. When the switch is open (ie

brakes NOT activated) the CJC icon is enabled and the Sample Rate Clock sends a

reading to memory every second. Additionally,. the 50mS Sample Rate Clock is

sampling at its primary rate which is set to 1 second.

When the brake pedal is depressed, the CJC icon is disabled and the 50mS Sample

Rate Clock driving the three Voltage icons (thermocouple inputs) switches to its

Alternate rate, storing readings to memory every 50mS.

After the data has been collected and downloaded to the PC, a Post-Processing Net

is constructed as shown in the following diagram.

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Omega-vehicle-security OMP-MODL Manuel d'utilisateur Page 274