Siemens SIMATIC S5 Manual page 226

QANF :
X
Specification of the first data word from which the data is to be read out of the specified source
Z-DB : D, KYx,y
Specification of the destination data block. For the programmable controllers S5-1 15U and S5-
150U it is not possible to program the data block type DX.
ZANF :
Specification of the first data word from which data will be written to the specified destination DB.
x = source first data word
DB165 :48 & y <
A source first data word is only required for modes 20, 22 and
24 (write jobs)
(n= max. 2047 words: max. data block length, the advisable
range is between O and 255)
x = data block type
x
x > c O: data block type DX
y = destination block number
DB : 5< y <255
DX : 1 < y <255
For modes 64 to 70 (read jobs) the specified data block
(destination DB) is in the PC memory.
O <y & 2 5 5
For modes 20 to 23 (write and delete jobs) the specified data
block (destination DB) is in the RAM of the positioning
module.
x = destination first data word
n
O
DB165 : 48&y <
a destination first data word is only required for modes 64 to 70
(read jobs)
(n= max. 2047 words: max. data block length, the advisable
range is between O and 255)
Standard Function Block FB165
6 - 3 3