User Manual

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