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Operating control interface units using the 3964R protocol
The control system terminates the reception when it receives the character sequence
DLE ETX BCC. It compares the block check character (BCC) received with the built-
in longitudinal parity. If the block check character is correct, and no other receive er-
rors have occurred, the control system transmits DLE. If the BCC is incorrect, NAK is
transmitted to the control interface unit, and a repetition of the process is awaited. The
control system terminates the reception if the data block cannot be received without
error after a (programmable) number of attempts, or if the repeat transmission is not
initiated within the (programmable) block delay time.
8.1.3 Basic structure of all messages
1.) Without Interpreter RK512
host
2.) With Interpreter RK512, communication involving FETCH messages
host
Subject to reasonable modifications due to technical advances.
Pepperl+Fuchs Group • Tel.: Germany (06 21) 7 76-0 • USA (330) 4 25 35 55 • Singapore 7 79 90 91 • Internet http://www.pepperl-fuchs.com
IDENT-I • IVI-KHA6-4HRX, IVI-KHD2-4HRX
device
STX
DLE
Command, DLE, ETX, BCC
DLE,
STX
DLE
Data, DLE, ETX, BCC
DLE
device
STX
DLE
Message head, DLE, ETX, BCC
DLE,
STX
DLE
Response message head, data, DLE, ETX, BCC
DLE
Copyright Pepperl+Fuchs, Printed in Germany
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