Diagnostics
7-2
IM 178-4
C79000-G7076-C178-01
Tabelle 7-1 ON Status LED and Diagnostic LEDs on the IM 178-4, continued
SF
BF
ON
SF: red
BF: red
ON: green
LEDs
Meaning
Remedy
ON
BF
SF
g
y
*
Transmission rate search or illegal
PROFIBUS address
Causes:
S
The watchdog time has elapsed
S
Bus communication via PROFIBUS
DP to the IM 178-4 is interrupted
Set a valid PROFIBUS address (1 to
125) on the IM 178-4 or check the bus
structure.
S
Check whether the bus connector is
correctly plugged in.
S
Check whether there is a break on
the LAN cable to the DP master.
S
Turn the switch for 24 V DC on the
power supply module off and on
again.
*
External error on a channel or a
channel was not assigned error-free
parameters.
Check the peripherals of the channels,
check the parameter assignment
Data exchange between the DP master
and IM 178-4 is taking place.
Both channels are free of errors.
–
*
Note relevant
off
lit
flashing
Breakdown of Bus Communication
If there is a breakdown of communication on PROFIBUS DP, for example caused
by the failure of the DP master, the digital outputs are deactivated (value 0 is
output) and 0 V is applied to the analog outputs. The diagnostic LED BF is lit (see
Table 7-1).