BECKHOFF C1300 - Manual (Page 8)

C1300 VME to II/O Interface Unit Beckhoff II/O-System
Page 8 of 44 Version : 2.01 Date : 18.12.95
The contents of the telegram is mainly organized for each byte.
AD0 - AD7 create the address field.Using this address field up to 254 modules can be
addressed ( Address 00h and 0fh are reserved. ).
CR0 - CR3 define the type of telegram. Following functions can be defined in the telegram:
CR3 CR2 CR1 CR0 Function Beschreibung
0 0 0 0 READ The modul addressed writes the entry data into
the Data fields D0 - D3 .
0 0 0 1 READ/WRITE The modul addressed writes the entry data into
the Data fields D0 - D3 and loads the
Ausgangsinformation.
0 0 1 0 ADDRESS INITIALIZITION The module addressed loads the contents of D0
as a module address und sets D0 = 0.
0 1 0 0 ADDRESS CHECK AND
COUNT COMMAND Each module passed increases the contents of
D0 by 1. The module addressed is loads the
contents from D0 into D3.
1 0 0 1 LOW INTENSITY
COMMAND The module addressed reduces the transmission
intensity by 20%.
picture 3:Controlfield
Byte D0 - D3 contain the actual Data to use. The processing of this data is determined by the
controll field.
The last Byte in a telegram contains two spare bits and 6 bits to create a CRC checksum. The
contents, having a length of 50 bits, achieves a Hamming distance of d = 3.