Rockwell Automation 1329I DeviceNet Option FRN 1.XXX - Manual (Page 43)

Chapter
6
Using Explicit Messaging
This chapter provides information about using explicit messaging. It
includes information on the following:
Important: In order to use explicit messaging, you must have already
configured the 1329I unit and DeviceNet option ( Chapter 3 )
and the scanner ( Chapter 4 ).
About Explicit Messaging Explicit messaging is a way of configuring and monitoring a slave device’s
parameters on the DeviceNet network. This form of messaging is performed
by copying data to and from the SLC controller M0 and M1 file. Explicit
messaging can only be done by the SLC controller to slave devices that are
mapped in the scanner module’s scan list.
Using Explicit Messaging With an SLC 500, there are five steps to the explicit messaging process.
1. Format an M0 file transfer in the processor to send an explicit message
request to the scanner module (download).
2. The scanner module transmits the explicit message request to the slave
device over the DeviceNet network.
3. The slave device transmits the explicit message response back to the
scanner and is queued into a file transfer buffer.
4. The processor uses an M1 file transfer to retrieve the explicit message
response from the scanner’s buffer (upload).
5. Format an M0 file transfer with a Delete Response Command, and use
the current transaction ID read in step 4. The transaction IDs are deleted
and can be reused.
Important: There must be a request message and an response message
whether you are reading or writing a parameter.
Topic Page
About Explicit Messaging 6-1
Using Explicit Messaging 6-1
Formatting Explicit Messages 6-2
Example SLC Ladder Logic Program 6-3