Siemens SIMATIC User Manual

Analog modules
6.9 Analog input module SM 331; AI 8 x RTD; (6ES7331-7PF01-0AB0)
S7-300 Module data
394 Manual, 06/2017, A5E00105505-AJ
Cycle time extension due to wire-break monitoring
The wire-break monitoring software function of the module is available in all operating
modes.
The cycle time of the module is doubled in 8-channel mode (hardware or software filter),
irrespective of the number of channels at which wire-break monitoring is enabled.
In 4-channel mode (hardware filter), the module interrupts processing of input data for the
duration of 100 ms and performs a line continuity check. That is, each line continuity check
extends the module cycle time by 100 ms.
Unused channels
In order to avoid incorrect measurements, an unused channel from an active group of
channels must be configured. Connect a resistor of the nominal range to the unused channel
in order to suppress diagnostics errors.
Set the "disabled" value at the "measurement type" parameter for unused channels. This
setting reduces module cycle times.
Short-circuit to M or L
The module does not suffer any damage if you short-circuit an input channel to M or L.. The
channel continues to output valid data and does not report a diagnostics event.
End of cycle interrupt
You can synchronize a process with the conversion cycle of the module by enabling the end
of cycle interrupt. The interrupt is set when all active channels have been converted.
The table below shows the contents of the 4 bytes of additional OB40 information during
process or end of cycle interrupts.
Content of the 4 bytes with additional infor-
mation
2
7
2
6
2
5
2
4
2
3
2
2
2
1
2
0
Byte
Special
analog flags
2 bits per channel to identify the range
High limit exceeded at channel
7 6 5 4 3 2 1 0 0
Low limit exceeded at channel
7
6
5
4
3
2
1
0
1
End of cycle event
X
2
Free bit
3
Programming restrictions when operating SM 331; AI 8 x RTD with PROFIBUS masters which only
support DPV0.
Certain parameters are not allowed when operating the SM 331; AI 8 x RTD analog input
module on an ET 200M PROFIBUS slave system and the PROFIBUS master is not an S7
master.. Non-S7 masters do not support process interrupts. All parameters associated with
these functions are disabled for this reason. This includes process interrupt enable,
hardware restrictions and end the enabling of cycle interrupts. All other parameters are
allowed.

Siemens SIMATIC Specifications

General

Product type designation	SIMATIC
CPU	Varies by model
Memory	Varies by model
Input/Output	Varies by model
Communication	Varies by model
Programming Language	STEP 7
Operating Temperature	0°C to 60°C (varies by model)
Protection Class	IP20
Category	Programmable Logic Controller (PLC)