Siemens 500 NIM - Manual (Page 91)

NIM Primitives 4-38 SIMATIC TIWAY I Series 500 NIM User Manual
Series 500 NIM Primitive Descriptions (continued)
Availability: Releases 2.1, 2.2, and 3.0
Primitive 21 is a command to read several random blocks of contiguous
memory.
Request: LLLL 21 TT NNNN AAAA
(repeated)
Symbol Value Definition
TT Data element type
NNNN Number of locations
AAAA Data element location
Response: LLLL 21 HH XX BB DD ... DD
(repeated)
(repeated XX times)
Symbol Value Definition
HH Attached device operational status
XX Number of blocks not processed due to error
BB Block numbers not processed due to error
DD Data requested
The BB field contains a value only when the P/C is reporting a P/C error.
NOTE: No data will be returned for the blocks that were in error.
Read Random
Block Primitive –
Code 21