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Performance Limits with 3964(R)
Performance Limits of the 3964(R) Procedure:
● Further processing of the send/receive data by the PLC program in the communication
partner is not guaranteed. You can only ensure this by using a programmable
acknowledgment mechanism.
● The block check of the 3964R procedure (EXOR operation) cannot detect missing zeros
(as a whole character) because a zero in the EXOR operation does not affect the result of
the calculation.
Although the loss of an entire character (this character has to be a zero!) is highly
unlikely, it could possibly occur under very bad transmission conditions.
You can protect a transmission against such errors by sending the length of the data
message along with the data itself, and having the length checked at the other end.
Point-to-point connection CP 440 Installation and Parameter Assignment
Manual, 09/2007, A5E00057742-03
www.gkbpx.com
Basic Principles of Serial Data Transmission
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2.3 Transmission integrity
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