Siemens Simatic M7-400, Reference Manual

Page: 247 / 638

Analog Modules
5-31
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
5.5 Behavior of the Analog Modules
Introduction
In this section, you will find information on:
•
How the analog input and output values depend on the operating modes of the
CPU and the supply voltage of the analog module
•
The behavior of the analog modules depending on where the analog values lie
within the value range
•
The effect of errors on analog modules with diagnostics capability
•
The effect of the operational limit of the analog module on the analog input and
output value, as illustrated by an example
5.5.1 Effect of Supply Voltage and Operating Mode
The input and output values of the analog modules depend on the operating mode
of the CPU and on the supply voltage of the module.
Table 5-38 Dependencies of the Analog Input/Output Values on the Operating Mode of the CPU and the
Supply Voltage L+
CPU Operating
Mode
Supply Voltage L+ at
Analog Module
Output Value of the Analog
Output Module
Input Value of the
Analog Input Module*
POWER
ON RUN L+ present CPU values Measured value
ON
Until the first conversion...
•
after power-up has been
completed, a signal of 0
mA or 0 V is output.
•
after parameter
assignment has been
completed, the previous
value is output.
7FFF
H
until the first
conversion following
power-up or after
parameter assignment of
the module has been
completed
L+ missing 0 mA/0 V
POWER
ON STOP L+ present Substitute value/last value
(default values: 0 mA/0 V)
Measured value
ON
(default values: 0 mA/0 V)
7FFF
H
until the first
conversion following
power-up or after
L+ missing 0 mA/0 V
power-up or after
parameter assignment of
the module has been
completed
POWER
OFF – L+ present 0 mA/0 V –
OFF
L+ missing 0 mA/0 V –
* L+ only required with 2-wire transmitters