Siemens Simatic S7-400 - Manual (Page 279)

Analog Modules
5-63
S7-400, M7-400 Programmable Controllers Module Specifications
A5E00069467-07
5.16 Diagnostics of the Analog Modules
Programmable and Non-Programmable Diagnostic Messages
In diagnostics, we make a distinction between programmable and
non-programmable diagnostic messages.
You obtain programmable diagnostic messages only if you have enabled
diagnostics by parameter assignment. You perform parameter assignment in the
“Diagnostics” parameter block in STEP 7 (refer to Section 5.7).
Non-programmable diagnostic messages are always made available by the analog
module irrespective of diagnostics being enabled.
Actions Following Diagnostic Messages in STEP 7
Each diagnostic message leads to the following actions:
• The diagnostic message is entered in the diagnosis of the analog module,
forwarded to the CPU and can be read out by the user program.
• The error LED on the analog module lights.
• If you have enabled diagnostic interrupts in STEP 7, a diagnostic interrupt is
triggered and OB 82 is called (refer to Section 4.5).
Reading out Diagnostic Messages
You can read out detailed diagnostic messages by means of SFCs in the user
program (refer to the Appendix “Diagnostic Data of Signal Modules”).
You can view the cause of the error in STEP 7 in the module diagnosis
(refer to the STEP 7 online help system).
Diagnostic Message in the Measured Value of Analog Input Modules
Every analog input module supplies the measured value 7FFF
H
irrespective of the
parameter assignment when an error is detected. This measured value means
either Overflow, Malfunction or a channel is disabled.
Diagnostic Message via the INTF and EXTF LEDs
Some analog input modules indicate faults by means of their two fault LEDs INTF
(internal fault) and EXTF (external fault). The LEDs go out when all the internal and
external faults have been eliminated.
Refer to the technical specifications of the modules, starting at Section 5.18, to find
out which analog input modules have these fault LEDs.