Balluff BTL7-T500 Series, Configuration Manual

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4
Configuration (continued)
4.9.2 Telegram Read.req
The Read.req is used for requesting the result of the action
that was initiated by the Write.req. The result is returned in
the Read.res. The Read.req is usually automatically sent by
the master and then the read.res only needs to be
processed.
The slave responds to the Read.req with a Read.res.
Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7 Byte 8 Bytes 9…n–2 Byte n–1 Byte n
SD LE LEr SD DA SA FC DSAP SSAP DU FCS ED
16#68 X X 16#68 16#8 16#8 X 16#30 16#32 SeeTab. 4-13 X 16#16
Tab. 4-12: Read.req
Byte No. Data type Meaning Description Value
0 Byte DP request Service code
16#5E= Read
16#5E
1 Byte Slot 0 16#0
2 Byte Index 47 16#2F
3 Byte Length Length of message to write
4 Byte Request Reference Freely selectable reference 16#1…FF
5 Byte Request ID 16#01 = Read
16#02 = Write
6 Byte Axis/DO-ID 16#00 = PROFIBUS access 16#0
7 Byte No. of parameters Limited by telegram length
16#01…16#27
8 Byte Error Code/Data
Format
16#44 = Error
For other formats see Standard data types
according to IEC 61158-5:2003 on page 12
16#10
9 Byte No. of values No. of values read (when Error 1)
10…n Return value(s) of the parameter. When an error
occurs the error number is contained in bytes 12
and 13 (see Tab. 4-14)
Tab. 4-13: DU Read.req
BTL7-T500-…
Configuration Guide