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II - DCE FEL ČVUT v Praze

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4.8.6 User Data Interface<br />

Input Area (Read)<br />

Structure of the<br />

user data<br />

I/O Modules with Intrinsically-Safe Signals<br />

C79000-G7076-C152-04<br />

The following figure shows the structure of the user data area for the HART<br />

analog input module. The data for the user data area can be read in the<br />

desired format using “Read peripheral data” (for example, L PIW 256) and<br />

evaluated in your user program.<br />

Byte 0<br />

Byte 1<br />

Byte 2<br />

Byte 3<br />

Byte 4<br />

Byte 5<br />

Byte 6<br />

Byte 7<br />

Value in S7 format<br />

Value in S7 format<br />

Channel 0<br />

Analog input value (with AI HART)<br />

Readback value (with AO HART)<br />

Channel 1<br />

Analog input value (with AI HART)<br />

Readback value (with AO HART)<br />

Main process quantity (primary<br />

variable): process value as floating<br />

point - as specified in HART for<br />

channel 0<br />

Value in IEEE754 floating-point format<br />

HART code for the<br />

Byte 8<br />

physical size of the HART<br />

variables for channel 0<br />

7 6 5 4 3 2 1 0<br />

Byte 9 0 Data ready bit = 1 indicates that<br />

there are unread response data in<br />

Bit no. client no.<br />

the transfer area of the client.<br />

Byte 10<br />

Byte 11<br />

Byte 12<br />

Byte 13<br />

Byte 14<br />

Byte 15<br />

Fig. 4-20 Input user data area of the HART analog modules<br />

SIMATIC S7 HART Analog Modules<br />

Data for channel 1:<br />

structure: analog to channel 0,<br />

bytes 4 - 9<br />

4-37

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