Siemens SIMATIC ET 200AL, System Manual

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What you should know about analog technology
2.14 Diagnostics
Analog value processing
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Function Manual, 06/2014, A5E03461439-AC
2.14 Diagnostics
Diagnostics for analog modules
SIMATIC analog modules can diagnose errors. A number of different types of diagnostics
are available for analog modules in STEP 7. Please note that the parameter assignment
options vary depending on the analog module and product family used. More detailed
information on the types of diagnostics can be found in the device manual for your analog
input or analog output module.
Proceed as follows to select the diagnostics types of the analog module used:
1.
Open STEP 7.
2. Select the analog module in the Device view.
3. Select the "Properties" tab.
4. Select the inputs or the required channel of the analog module in the Inspector window.
Table 2- 2 Overview of diagnosable errors
Type of diagnostics Analog input module Analog output module
Wire break ✓ ✓
No supply voltage L+ ✓ ✓
Overflow ✓ ✓
Underflow ✓ ✓
Common mode error ✓ -
Short-circuit ✓ ✓
Overload - ✓
Reference junction ✓ -
Diagnostics of the analog module are carried out while the system is in operation, on the
basis of the current output variables such as current or voltage. If the output current or output
voltage is no longer sufficient, the module will not be able to run reliable diagnostics. The
limits within which diagnostics are possible are specified in the technical data for each
module.
The module reports the diagnosed state to the CPU using a diagnostics error interrupt. If
several diagnostics are pending at the same time, the diagnostics with the highest priority is
reported to the CPU first. Diagnostics are output on LED displays on the affected module, on
the CPU display, on the Web server or on an HMI device.
The configurable diagnostics types depend on the respective selected measuring type or
output type. The following tables shows the relationship between the diagnostics types,
measuring types or output types of an analog input module or analog output module.