IDENT-I • IRI-KHD2-4.RX, IRI-KHA6-4.RX
Operating control interface units using the 3964R protocol
Subject to reasonable modifications due to technical advances.
Copyright Fuchs, Printed in Germany
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
Da
te
of
issue
27.
0
2
.2002
28
3.) With interpreter RK512, communication involving send-messages
8.1.4
Data exchange via FETCH messages involving 3964R with RK512
This type of data exchange is possible only in the basic fixed code operating mode.
The first time a FETCH message is received, the control interface unit switches into
a "Read" mode in which all read heads connected to the control interface unit are in-
terrogated continuously.
For each correctly received FETCH message, the control interface unit returns a re-
sponse message, in which the status of all 4 read heads (always 20 bytes) is trans-
mitted.There are 5 bytes for each read head. The data length for a read head is the
same whether or not a code has been read.
Each head has a "Read Sequence number" (8 bits) which is incremented whenever
• two codes are read in succession, and the first differs from the second
• two identical codes are read in succession, and the first of these has been trans-
mitted to the control system
Bild 8.1:
Structure of message data
host
device
STX
DLE
Message head, command, DLE, ETX, BCC
DLE, STX
DLE
Response message head, DLE, ETX, BCC
DLE
STX
DLE
Message head, data, DLE, ETX, BCC
DLE, STX
DLE
Response message head, DLE, ETX, BCC
DLE
Byte1...Byte5
Byte6...Byte10
Byte11...Byte15
Byte16...Byte20
Data, Head 1
Data, Head 2
Data, Head 3
Data, Head 4
}
}
}
}
