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Message Transmission
6-1
Message Transmission
1,2,3...
Request
Request
Supported Messages
Message
Read byte block
Write byte blocK
Read word block
Write word block
Read network parameter
Write network parameter
Run/stop command
Read profile
Read communications log data
Clear communications log data
Echoback message
84
Message transmission is a function that supports the asynchronous ex-
change of data between nodes. The basic functions of message transmis-
sions are explained here.
1. When a node receives the token, it can send one (and only one) message
frame before transmitting cyclic data.
2. The volume of data that can be transmitted in one message frame is 1,024
bytes max.
3. An algorithm is used so that the allowable refresh cycle time for cyclic
transmission is not exceeded.
4. A message transmission can be sent either to a single destination node as
a 1:1 transmission or broadcast to all nodes on the network as a 1:N trans-
mission.
5. In 1:1 message transmissions, the destination node has an acknowledge-
ment function to check that data has been received successfully. No re-
sponse is provided by the source node for 1:N message transmissions.
Response
1:1 message transmission
Reception
1:N message transmission
1:1 transmission
Client function
Server function
No
No
No
No
Yes (See note 1.)
Yes
Yes (See note 1.)
Yes
No
Yes
No
No
No
No
No
Yes
No
Yes
No
Yes
Yes*
Yes
Reception
Reception
1:N transmission
Client function
Server function
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
No
Yes
No
No
Section 6-1
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