Pepperl+Fuchs IVI-KHA6-4HRX - Page 45

IDENT-I • IVI-KHA6-4HRX, IVI-KHD2-4HRX
Operating control interface units using the 3964R protocol
Subject to reasonable modifications due to technical advances. Copyright Pepperl+Fuchs, Printed in Germany
P
epperl+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
Date of issue 27.08.2001
43
Buffered auto read with read head number
Command initialization takes place once only, through the transmission of a SEND
message containing the command. A read head specified in the command will be in-
terrogated continuously. If a faulty read head is detected, the control interface unit
cancels the command, transmits the error status and waits for a further command. Er-
rors relating to communication between the read head and the code carrier (no code
carrier available) are suppressed.
Codes are transmitted only when:
• a new code is read
• at least 5 unsuccessful read attempts have occurred between two successful read-
ings of identical codes
Together with the code data, an 8-bit wide read sequence number is transmitted,
which is incremented whenever two non-identical codes are read in succession, or
when at least 5 unsuccessful attempts to read occur between the reading of two iden-
tical codes.
Bild 8.13: Message data for a read head after successful reading of a code
Example: A code was read at head 4, read sequence-no. 34h
Response: 21 08 4A 65 13 0C 34
Buffered auto read without read head number
The command description is the same as for the BAR command, except that all con-
nected read heads are interrogated continuously. After successful reading of a code
carrier, all connected read heads will be interrogated again, and all codes read will be
transmitted in a message.
Byte 1
High
Byte 2
Low
Byte 2
High
Byte 3
Low
Byte 3
Byte 4 ...
Byte Byte 7
21h 0 Head
Status
Head-no. Code Code Read
sequence-
no.
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