Simatic 505 SoftShop
5
••••
73
Bit
1
2
3
4
5
6
1 2 3 4 5 6 7 8 9
11
10 1213141516
15
16
17
18
19
20
Word inputs
Word outputs
Other word data
PGTS word
parameter area
Values are copied into the
word parameter area to be
used by the subroutine.
When parameters are
specified read/write,
changed values are copied
back into appropriate
memory areas.
Figure 5.4
User External Subroutine Memory
A block of memory within the controller may be allocated for storing
externally developed programs written in C, Pascal, Assembly language,
etc. This memory type is called User Memory (U-Memory). The size of
U-Memory is user configurable.
Global Memory: 575 Only
The 575 CPU allocates a 32K-word block of memory that allows you to
transfer data over the VME back-plane. This memory type is called
Global Memory (G-Memory). Refer to Appendix I of the processor
manual for more information about G-Memory.
VME Memory: 575 Only
The 575 controller also allows access to physical VME addresses using
the VMM-Memory or VMS-Memory.
•
VMM corresponds to VME address modifier 39 (standard non-
privileged data access).
•
VMS corresponds to VME address modifier 29 (short non-
privileged access).
The 575 controller allows you to use a VME address (VMM or VMS) as a
parameter to most word-oriented RLL instructions, e.g., ADD, SUB, or
MOVW, etc.
When a VME address is used and is not recognized by any installed board, a
VMEbus error occurs. If the instruction that used the address was other than
MOVE or XSUB (with the U-Memory header’s E bit set to 1--see Appendix H
in the Programming Reference Manual), the controller enters the Fatal Error
mode, freezes analog outputs and clears discrete outputs.
Use the XSUB or MOVE instruction to access the VME address
.
