Siemens 500 NIM - Manual (Page 79)

NIM Primitives 4-26 SIMATIC TIWAY I Series 500 NIM User Manual
4.8 Data Field Length Restrictions
Table 4-6 and Table 4-7 delineate the maximum length of the data field, in
bytes, for Read and Write Primitives.
Table 4-6 Maximum Read Primitive Byte Length
Read Primitive.
Maximum number of
Primitive request.
(When using extended
address)
20
269
269
21
268
268
51
265
265
52
265
265
56
268
268
57
268
268
bytes read per
Primitives requesting more than one data element type (TT) in a Primitive request
(possible with Primitives 05, 21, 51, 52, 56, and 57) must be verified to contain
a cumulative byte count of less than or equal to the byte counts in this table. Consult
Table 4-4 for the number of bytes per data element, and Table 4-5 for data element
locations.