4
Data Exchange between User Program and AS−i Slaves
50
CP 343−2 / CP 343−2 P AS−Interface Master
Release 08/2008
C79000−G8976−C149−04
Table 4-4
Address Area for the Analog Values of an AS-i Slave
Byte no. (start a offset)
Analog value channel
Start a 0
Channel 1 / high byte
Start a 1
Channel 1 / low byte
Start a 2
Channel 2 / high byte
Start a 3
Channel 2 / low byte
Start a 4
Channel 3 / high byte
Start a 5
Channel 3 / low byte
Start a 6
Channel 4 / high byte
Start a 7
Channel 4 / low byte
Analog A/B slaves with 2 channels occupy only half the address area. The A
slaves, in this case, occupy bytes 0−3 and the B slaves bytes 4−7.
Examples / notes on reading Table 4-3:
1. Configuration: analog slaves have AS-i addresses 1−6
You use data record 140 and specify 48 as the data record length.
2. Configuration: 1 analog slave with AS-i address 7 is used
You use data record 141 and specify 24 as the data record length.
3. Configuration: the entire address area for 31 analog slaves is used
You use data record 140 and specify 128 as the data record length. This covers
analog slaves 1−16.
For the other analog slaves 17−31, you use data record 144 in a second job
and specify 120 as the data record length.
4. Configuration: analog slaves are located in the address area 29−31
You use data record 147 and specify 24 as the data record length.
Representation of the analog values
The analog values are interpreted according to slave profile 7.3 or 7.4 as 16-bit
values in two’s compliment.
The transparent values are interpreted as two independent bytes.
For further information regarding the range of values, the measurement range and
the accuracy please refer to the relevant documentation of the analog slaves.