Rockwell Automation 20-750-PBUS Profibus DPV1 Option Module - Manual (Page 60)

60 Rockwell Automation Publication 750COM-UM004B-EN-P - September 2012
Chapter 6 Acyclic Messaging
Acyclic Messaging for
DPV1 Class 1 The 20-750-PBUS option module provides the following Profibus DPV1 Class 1
Acyclic Services:
• READ—This service is used to read a parameter in the PowerFlex 750-
Series drive or the option module.
• WRITE—This service is used to modify a parameter in the PowerFlex
750-Series drive or the option module.
Example Messaging Examples of using Profibus DPV1 Class 1, Acyclic Messaging to read and write a
drive parameter is described in this section.
Read Example for Drive Parameter 1 - [Output Frequency]
To read the PowerFlex 750-Series drive parameter 1 - [Output Frequency] using a
Class 1 Acyclic Read Service, setup a ControlLogix controller (with a MVI56-
PDPMV1 Profibus Master). After the master is setup, the ControlLogix tags
must be populated with the values to read the parameter as shown in
Figure 11 .
Drive Parameter 1 - [Output Frequency]:
• Slot Number = 0x00 + Quotient of (1 / 256) + 1= 1
• Index Number = Remainder of (1 / 256) = 1
• Length in bytes of the value of the parameter (32 bit floating point value) /
8 = 4
To test the Read service, you may manually enter the values as shown below into
the MVI56-PDPMV1 controller scoped tags, where a ProSoft MVI56-
PDPMV1 Profibus master module is installed in the backplane of the
ControlLogix controller rack.
• MVI56PDPMV1.Mailbox.AcyclicRead.Out.SlotNumber = 1
• MVI56PDPMV1.Mailbox.AcyclicRead.Out.SlaveAddress = 3
• MVI56PDPMV1.Mailbox.AcyclicRead.Out.Length = 4
• MVI56PDPMV1.Mailbox.AcyclicRead.Out.Index = 1
Next, manually enter a value of '1' into the
MVI56PDPMV1.MailboxCommand.AcyclicRead tag, to send the message.