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SIMATIC S7 HART Analog Modules
HART status bytes
4-14
Each HART command is followed by a HART response containing data and
status bytes (see 4.8.3). The status bytes provide information on:
Device status of the connected field device (e.g. modification of
parameters)
Communication error during transmission between HART analog module
and the connected field device
Command error during interpretation of the HART command by the
connected field device (warning, rather than error)
The HART status bytes are entered in the response data record unchanged
(see Section 4.8.3). Their significance is described in the technical
specifications for HART. You can use SFC59 to read the data records in your
user program.
4.5.2 Interrupts of the HART Analog Modules
Overview of the
interrupts
Hardware
interrupts with
AI HART
The general interrupt behavior of the HART analog module corresponds to
that of the other SIMATIC S7-Ex analog modules, see Section 3.6.5. You can
set parameters to enable or disable any interrupt (see Section 4.4).
There are two types of hardware interrupt: “Hardware interrupt when limit
value exceeded” and “Hardware interrupt on end of cycle.” When a hardware
interrupt is triggered, you can evaluate the local data in OB40:
Table 4-8 Local data in OB40
Local data
OB40
Bit
7 ...4
Bit
3
Bit
2
Bit
1
Bit
0
Limit exceeded
Byte 0 ‘0’ ‘0’ ‘0’ Channel 1 Channel 0 Upper limit exceeded
Byte 1 ‘0’ ‘0’ ‘0’ Channel 1 Channel 0 Lower limit exceeded
Byte 2 ‘0’ ‘0’ ‘0’ ‘0’ ‘0’ Not relevant
Byte 3 ‘0’ ‘0’ ‘0’ ‘0’ ‘0’ Not relevant
At the end of the cycle all the bits in bytes 0-3 of the additional information
for OB40 which are not reserved for channels 0 and 1 are set to ‘1’. You can
use the reserved bits to evaluate whether the upper or lower limit set has been
exceeded for a particular channel: if a limit has been exceeded, a ‘1’ is
displayed instead of a ‘0’.
I/O Modules with Intrinsically-Safe Signals
C79000-G7076-C152-04