Siemens DP/AS-Interface Link 20E Manual page 50

Data Exchange Between the DP Master and AS-i Slave
Byte Number *)
m+21
m+22
m+23
m+24
m+25
m+26
m+27
m+28
m+29
m+30
m+31
*)
m = start address of the input or output data on the DP master
**)
Bits 4–7 in the first byte of the input data are known as the status nibble; they are
reserved for the command interface of the DP/AS-i Link 20E (see Section 3.1).
Bits 4–7 in the first byte of the output data are also reserved and have no further
significance.
Masking I/O Addresses
I/O addresses that are not used in the lower part of the table can be masked
during DP configuration (for example in the STEP 7 configuration using the
"Reserved Length" parameter (see Section 1.9.3).
Example:
You are not using any B slaves as AS-i slaves with binary inputs and the highest
address of a standard slave is 20; this means that you can set the "Reserved
Length" of the input data to 11.
Special Feature of AS-i Analog Slaves
If you use AS-i analog slaves complying with profile 7.3 /7.4, the following applies:
S The input nibbles of these AS-i slaves are set to the value "0" by the DP/AS-i
Link 20E;
S The output nibbles of these AS-i slaves are ignored by the DP/AS-i Link 20E;
How to access AS-i analog slaves is described in Section 2.4.
50
Bits 7–4
Slave 10B
Slave 12B
Slave 14B
Slave 16B
Slave 18B
Slave 20B
Slave 22B
Slave 24B
Slave 26B
Slave 28B
Slave 30
Bit 3 | Bit 2 | Bit 1 | Bit 0
Bits 3–0
Slave 11B
Slave 13B
Slave 15B
Slave 17B
Slave 19B
Slave 21B
Slave 23B
Slave 25B
Slave 27B
Slave 29B
Slave 31B
Bit 3 | Bit 2 | Bit 1 | Bit 0
DP/AS-Interface Link 20E
Release 11/2002
C79000-G8976-C138–04