Basic Principles of Serial Data Transmission
2.6 Data Transmission with the ASCII Driver
CP 341 Point-to-Point Communication, Installation and Parameter Assignment
68
Manual, 09/2008, A5E02191071-01
Fixed message frame length end criterion
When receiving data, the end of the message frame is recognized when the assigned
number of characters have been received. The received data is accepted by the CPU.
If the character delay time expires before the assigned number of characters has been
reached, the receive operation is ended. An error message is generated and the message
frame fragment is discarded.
Note the following if the message frame length of the received characters does not conform
with the fixed assigned message frame length:
●
Message frame length of the received characters is greater than the fixed assigned
message frame length:
All characters received after reaching the fixed assigned message frame length are
either:
–
Discarded if the character delay time expires at the end of the message frame.
–
Merged with the next message frame if a new message frame is received before the
character delay time expires.
●
Message frame length of the received characters is less than the fixed assigned message
frame length:
The message frame is either:
–
Discarded if the character delay time expires at the end of the message frame.
–
Merged with the next message frame if a new message frame is received before the
character delay time expires.
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