Rockwell Automation 20-750-CNETC PowerFlex Coaxial ControlNet Option Module User Manual
Page 84
84
Rockwell Automation Publication 750COM-UM003B-EN-P - November 2012
Chapter 6
Using Explicit Messaging
ControlLogix – Formatting a Message to Write Multiple Parameters
Figure 28 - Scattered Write Multiple Message Configuration Dialog Boxes
The following table identifies the data that is required in each box to configure a
message to write multiple parameters.
Configuration Tab
Example Value
Description
Message Type
Service Type
(1)
Service Code
(1)
Class
Instance
Attribute
(2)
Source Element
Source Length
Destination
CIP Generic
Custom
4e (Hex.)
93 or 9F (Hex.)
(4)
0 (Dec.)
0 (Hex.)
Scattered_Write_Request
(5)
40 bytes
(5)
Scattered_Write_Response
(6)
Used to access the DPI Parameter Object in the option module.
Required for scattered messages.
Code for the requested service.
Class ID for the DPI Parameter Object.
Required for scattered messages.
Required for scattered messages.
Name of the tag for any service data to be sent from scanner to the option module/drive.
Number of bytes of service data to be sent in the message.
The tag where the data that is read is stored.
Communication Tab
Example Value
Description
Path
(3)
My_PowerFlex_755_Drive
The path is the route that the message will follow.
Tag Tab
Example Value
Description
Name
Scattered_Write_Message
The name for the message.
(1) The default setting for Service Type is ‘Custom’, enabling entry of a Service Code not available from the Service Type pull-down menu. When choosing a Service Type other than ‘Custom’ from
the pull-down menu, an appropriate Hex. value is automatically assigned to the Service Code box which is dimmed (unavailable). When writing to 32-bit REAL (floating point) parameters, as
in this example, data conversion using COP (Copy) instructions or UDDTs is required to correctly write the parameter values.
(2) Scattered writes always write parameter values to the drive’s Nonvolatile Storage (EEPROM) memory, which retains these values even after the drive is power cycled. Important: Be very
cautious as the EEPROM may quickly exceed its life cycle and cause the drive to malfunction.
(3) Click Browse to find the path, or type in the name of the device listed in the I/O Configuration folder (for this example, My_PowerFlex_755_Drive).
(4) See
Table 4 on page 74
for limitations of PowerFlex 750-Series drives when using DPI Parameter Object Class code 0x93 or Host DPI Parameter Object Class code 0x9F for explicit messaging.
(5) In this example, we are writing to five 32-bit REAL (floating point) parameters. Each parameter being written to requires two contiguous DINT registers. Therefore, a controller tag was created
with its Data Type field set to the name of the UDDT of five interleaved DINTs and REALs. Also, the Source Length field on the Message Configuration dialog box must correspond to the selected
Data Type in bytes (for this example, 40 bytes for an array of five scattered REAL structures). Scattered write messages always assume that every parameter being written to is a 32-bit
parameter, regardless of its actual size. Maximum message length is 256 bytes which can write up to 32 parameters, regardless of their size. For parameter numbering, see
(Class code 0x93) or
Host DPI Parameter Object on page 129
(Class code 0x9F).
(6) The controller tag for ‘Scattered_Write_Response’ must be the same size as the controller tag for ‘Scattered_Write_Request’ (for this example, 40 bytes). An array of DINTs is suggested to be
able to read any error codes that are returned.