3 stopping the drive, 4 setting the frequency, 5 writing values to a vtac 7 register – Rockwell Automation 2LW3000 LonWorks Communication Option Module for VTAC 7 Drives User Manual
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8-2
LonWorks Module for VTAC 7 Drives
8.3
Stopping the Drive
The drive will stop using the stop mode selected in parameter P.025 if
any of the
following conditions are met:
•
NviSpeedStpt.state is set to any value but 1
•
The node is brought offline
•
RQ_DISABLED is requested in nviObjRequest
8.4
Setting the Frequency
The actual value written to the LonWorks module =
(nviDrvSpeedStpt*0.5*nviDrvSpeedScale*0.005*nciNmlFreq*100) / (100*100)
Notes for above equation:
•
Multiplied by 0.005 and 0.5 to scale the two LonWorks format values
•
Nominal frequency is the base for scale and setpoint percent values
•
Multiplied by 100 to fit LonWorks module format.
•
Divided by (100*100) because the setting frequency is multiplied by two percent
values.
Refer to chapter 7 for information about nviSpeedStpt and nviSpeedScale.
8.5
Writing Values to a VTAC 7 Register
To write a value to a VTAC 7 register:
Step 1. Change register in nciWriAddr.
Step 2. Change value in nciWriValue.
Changing the value in nciWriValue triggers the writing to a register in the LonWorks
module. Changing the address alone will not perform a write sequence.
To verify that the LonWorks module has accepted the value written to it, read it back
by setting nciRdAdr to the corresponding DP RAM feedback register. See Appendix B
for a list of registers.
NviSpeedScale
NviSpeedStpt.value
NviSpeedStpt.state
Resulting Speed
0%
0%
1
0 Hz
100%
0%
1
0 Hz
0% 100%
1
0
Hz
150%
100%
0
(Normal) Stop
150%
100%
1
1.5*1.0*Nomfreq
-75%
100%
1
-0.75*1.00*Nomfreq
150%
50%
1
1.5*0.50*Nomfreq