Siemens SIMATIC ET 200iS, Manual

Page: 132 / 434

Commissioning and Diagnostics
ET 200iS Distributed I/O Station
7-16
A5E00087831-02
7.6 Diagnostics Using the Process Image Input Table
Introduction
In addition to the diagnostic information available with the LEDs and module/DP
diagnostics, the module also provides information about the validity of every input
signal – the value status. The value status is entered in the process image along
with the input signal.
Value Status of the Digital Input Modules
The value status is additional binary information on a digital input signal. The value
status is entered in the process image input table at the same time as the process
signal and provides information on the validity of the input signal. The value status
is influenced by the following:
•
Wire break check / short circuit
•
Flutter monitoring
•
Pulse extension
•
Validation check of changeover contacts
Significance of the value status:
•
“1“: Input signal is valid
•
“0“: Input signal is invalid
Digital Input and Value Status Assignment
In the process image, a value status is assigned to every input in the input byte IB
x of the module.
Input signal channel 1
Meaning of value status: 1: signal valid
0: signal invalid
Input signal channel 0
IB x
7 6 5 4 3 2 1 0
Value status for channel 1
Value status for channel 0
Input signal channel 2
Input signal channel 3
Value status for channel 2
Value status for channel 3
Figure 7-4 Assignment of the Value Status to the Digital Input