Technical data

Linkage with PLC
CP 486 ⋅ 00/14 VIPA GmbH 155
6.4.2.9 Read Area of Process Image
Register
high In low Out
AX $71 typr status
BX adr
CX len
SI offset
DS segment
typ data type of process image (EB, MB)
adr initial address in area
len number of data in bytes or words (depending on TYPE)!!
offset offset of data address (in AT)
segment segment of data address (in AT)
status < 0 error number because of error
= 0 process image not available
> 0 counter for process image (as for status function)
This function is used to read an area of the current process image. When accessing single areas, then
the length of the area is supervised, e.g. cannot be read from EB126 with the length of 4 bytes
because only 128 byte EB are available.
The length is input in words for timer and counter access, and in bytes for all other types. For timer
and counter the high- and low byte of every word is exchanged also at the transfer, so that the data
in the AT can be correctly processed as words.
By setting the type ABSOLUT, an optional process image sector can be read, also affecting other
areas. The length is given in bytes, also if it is read from timer or counter range. If a range of timer
or counter is read, then high- and low byte is changed again, too !!
Tab. Data types for process image:
06 counter (length in words)
07 timer (length in words)
08 marker (length in bytes)
09 EB (length in bytes)
0A AB (length in bytes)
0F absolute access to process image (length in bytes)