Diagnostics With The Cp 340 - Siemens SIMATIC CP 340 User Manual

Diagnostics with the CP 340

Introduction
The diagnostics functions of the CP 340 enable you to quickly localize any errors which
occur. The following diagnostics options are available:
● Diagnosis via the Display Elements of the CP 340
● Diagnosis via the STATUS output of the function blocks
● Diagnosis via the S7-300 backplane bus
● Diagnostics by means of the diagnostic buffer of the CP 340
Display elements (LED)
The display elements show the operating mode or possible error states of the CP 340. The
display elements give you an initial overview of any internal or external errors as well as
interface-specific errors (see Chapter "Diagnosis via the Display Elements of the CP 340
(Page 133)").
STATUS Output of the FBs
The P_SEND, P_RCV and P_PRINT function blocks have a STATUS output for error
diagnostics. Reading the STATUS output of the function blocks gives you information on
errors which have occurred during communication. You can evaluate the STATUS output in
the user program (see Chapter "Diagnostics Messages of the Function Blocks P_SEND,
P_RCV and P_PRINT (Page 134)").
The CP 340 also enters the diagnostic events at the STATUS output in its diagnostic buffer.
S7-300 backplane bus
The CP 340 can trigger a diagnostics alarm on the CPU assigned to it. CP 340 provides
4 bytes of diagnostics information at the S7-300 backplane bus. This information is analyzed
via the user program (OB 82) or using a programming device to read from the CPU
diagnostic buffer (see Chapter "Diagnostics via the S7-300 backplane bus (Page 142)").
The CP 340 also writes diagnostic events which have triggered a diagnostics interrupt to its
diagnostic buffer.
If a diagnostics alarm event occurs, the SF LED (red) lights up.
PtP coupling and configuration of CP 340
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