Rockwell Automation T8444 Trusted TMR Pulse Generator and Monitoring Module - Manual (Page 40)

Trusted
TM
Module T8444
Issue 09 Apr 10 PD-T8444 40
6.12. Inference of Position from Motor Pulses
Position is inferred by counting the number of pulses generated by the module (not the number of
Pulses fed back from the motor drivers). All 6 phases are be used to operate the counter. The counter
counts up when the Rod is withdrawn and down when the Rod is inserted. A count of Zero is expected
to be with the rod at rest and fully inserted.
6.13. Number of Pulses for a full transition of a rod from End to End
In one installation each rod is required to move slightly less than 12 feet. For the purposes of the
calculation we will utilise 12 feet. Each rotation of the motor moves the rod 0.75 Inches ergo 192
rotations moves the rod from end to end. Each rotation of the rod requires 2 pulses from each output
therefore each output must pulse 192*2 times = 384 Therefore if all pulses are counted the total will be
384*6 = 2304 pulses.
Because of potential position registration errors the Counter has been configured so that it can count
above the expected maximum and below Zero. The maximum count values are +32767 to –32768.
The actual values which represent 0 to 100% movement are specific to each application and must be
calculated from the mechanics of the Rod and motor system.
6.14. Synchronisation/External timing
No effort is made to synchronise signals between motors.
6.15. Setting of Count Position
Two methods exist for zeroing the rod position counter. The counter can be manually incremented or it
can be preset to a particular value from the Trusted
TM application.
Position
Manual increments can be made by jogging the displayed position up or down under control of the
Trusted
TM application. Typically the application would receive an input from a switch on the control
matrix which would request “Jog up” or “Jog down”. The application then passes this command on to a
selected channel in a selected module and causes the position count to increment or decrement.
Alternatively a position register can be set up in the Trusted
TM controller which can be loaded to the
PGM in a single action.
Zero/Reset
The counter can be caused to Zero/Reset by the application of a signal from the Trusted
TM application.
As with incrementing the position this control is expected to be from a MMI of some sort via the
Trusted
TM application.
6.16. Analogue Input Discrepancy
Detected on a per channel basis if one or more slices’ analogue values deviate outside a preset
window for more than a set number of samples.
6.17. Output 2-oo-3 error
Detected by loss of current flow in one slice when commanded on.