Rockwell Automation 1747-SDN SLC 500 DeviceNet Scanner Module User Manual - Manual (Page 144)

Publication 1747-UM655B-EN-P - June 2007
144 Explicit Message Program Control
How the Explicit Message Program Control Feature Works
1. Format an M0 file transfer in the processor to send an Explicit
Message Request to the module (download).
2. The 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 the current transaction ID read in step 4.
The transaction IDs are deleted and can be reused.
4
5
1
3
2
MO file transfer (including words 224…255)
(sent from processor to module).
M1 file transfer (including words 224…255)
(sent from module to processor).
Explicit Message - A message used to
transmit commands, data, requests for
data or responses. The message is sent
from a client on the DeviceNet network
to a server on that network.
Response - An explicit message sent by a
server to a client in response to the
client’s request. For every request issued,
there is a response.
Request - An explicit message sent by a
client to a server requesting the server
to perform a function.
M1 file transfer is
completed. TXIDs are
deleted and can be reused.
Master’s Explicit
Request
DeviceNet
Drop Line
Slave’s Explicit
Request
1203-GK5
Communication
Adapter
1305 AC Drive
DeviceNet Trunk Line