II - DCE FEL ČVUT v Praze

4.8.6 User Data Interface
Input Area (Read)
Structure of the
user data
I/O Modules with Intrinsically-Safe Signals
C79000-G7076-C152-04
The following figure shows the structure of the user data area for the HART
analog input module. The data for the user data area can be read in the
desired format using “Read peripheral data” (for example, L PIW 256) and
evaluated in your user program.
Byte 0
Byte 1
Byte 2
Byte 3
Byte 4
Byte 5
Byte 6
Byte 7
Value in S7 format
Value in S7 format
Channel 0
Analog input value (with AI HART)
Readback value (with AO HART)
Channel 1
Analog input value (with AI HART)
Readback value (with AO HART)
Main process quantity (primary
variable): process value as floating
point - as specified in HART for
channel 0
Value in IEEE754 floating-point format
HART code for the
Byte 8
physical size of the HART
variables for channel 0
7 6 5 4 3 2 1 0
Byte 9 0 Data ready bit = 1 indicates that
there are unread response data in
Bit no. client no.
the transfer area of the client.
Byte 10
Byte 11
Byte 12
Byte 13
Byte 14
Byte 15
Fig. 4-20 Input user data area of the HART analog modules
SIMATIC S7 HART Analog Modules
Data for channel 1:
structure: analog to channel 0,
bytes 4 - 9
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