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CP 521
Sending fixed-length messages
The following is a description of which jobs the CPU uses when prompting the
CP 521 to send messages and how the CP 521 acknowledges these jobs. Table 7-13
contains all the CPU jobs permissible in ASCII mode. After setting the interface
parameters (90
) ( 7.3), jobs A0
H
Table 7-13. Permissible CPU Job Requests when Sending Messages (PIQ)
Byte 0
00
Data not relevant
H
10
Set date and time of day; variable in bytes 1 to 7
H
90
Set interface parameters
H
A0
Coordinate data transfer
H
B0
Process data transfer CPU CP
H
Data is transferred via the CP 521 in two steps:
•
First, data transfer between the CPU and the CP 521 is coordinated
•
Only then is data transferred.
The schematic on the following two pages shows the overall data transfer
procedure for sending data.
Data blocks of eight bytes are represented as used for sending messsages. The
CPU job varies from block to block and also the corresponding acknowledge-
ment from the CP 521:
GWA 4NEB 812 6030-02b
and B0
are relevant for sending data.
H
H
Meaning
ASCII Mode
7-21
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