Siemens SIMATIC S7-1200 - Page 983

Communication
11.4 AS-i
S7-1200 Programmable controller
System Manual, V4.2, 09/2016, A5E02486680-AK
983
The digital input module (AS-i SM-U, 4DI) in the AS-i network above has been assigned I/O
address 2. By clicking on the digital input module, the "I/O addresses" tab in the device
"Properties" displays the I/O address, as shown below:
You can access the data of the AS-i slaves in the user program by using their I/O addresses
with the appropriate bit logic operations (for example, "AND") or bit assignments. The
following simple program illustrates how the assignment works:
Input 2.0 is polled in this program. In the AS-i system, this input belongs to slave1 (Input byte
2, bit 0). Output 4.3, which is then set, corresponds to AS-i slave 3 (Output byte 4, bit 3)
Transferring AS-i analog values
You can access analog data of an AS-i slave through the process image of the CPU if you
have configured this AS-i slave in STEP 7 as an analog slave.
If you did not configure the analog slave in STEP 7, you can only access the data of the AS-i
slave through the acyclic functions (data record interface). In the user program of the CPU,
AS-i calls are read and written using the RDREC (read data record) and WRREC (write data
record) distributed I/O instructions.
Note
A configuration of the AS
-i slaves specified through STEP 7 and downloaded into the S7
station is transferred by the CPU on the AS
-i master CM1243-2 during S7 station start-up.
Any existing config
uration that was determined through the "System assignment" online
function
(Page 981) ("ACTUAL -> EXPECTED") will be overwritten.
Further information
You can find detailed information on the AS-i master CM 1243-2 in the "AS-i master CM
1243-2 and AS-i data decoupling unit DCM 1271 for SIMATIC S7-1200" Manual
(http://support.automation.siemens.com/WW/view/en/50414115/133300).