Siemens SIMATIC S7-200

S7-200 Specifications
A-60
S7-200 Programmable Controller System Manual
A5E00066097-02
EM 277 PROFIBUS-DP LED Status Indicators
The EM 277 PROFIBUS-DP module has four status LEDs on the front panel to
indicate the operational state of the DP port:
• After the S7-200 CPU is turned on, the DX MODE LED remains off as long as
DP communication is not attempted.
• Once DP communication has been successfully initiated (the EM 277
PROFIBUS-DP module has entered data exchange mode with the master), the
DX MODE LED turns green and remains on until data exchange mode is
exited.
• If DP communication is lost, which forces the EM 277 module to exit data
exchange mode, the DX MODE LED turns OFF and the DP ERROR LED turns
red. This condition persists until the S7-200 CPU is powered off or data
exchange is resumed.
• If there is an error in the I/O configuration or parameter information that the DP
master is writing to the EM 277 module, the DP ERROR LED flashes red.
• If user 24 VDC is not provided, the POWER LED will be off.
Table A-20 summarizes the status indications signified by the EM 277 status LEDs.
Table A-20 EM 277 PROFIBUS-DP Module Status LEDs
LED
OFF RED FLASHING RED GREEN
CPU Fault
Module is good Internal Module
Failure
-- --
POWER
No 24 VDC
User Power
-- -- 24 VDC User
Power Good
DP ERROR
No Error Left Data
Exchange Mode
Parameterization/
Configuration Error
--
DX MODE
Not in Data
Exchange Mode
-- -- In Data
Exchange Mode
Note When the EM 277 PROFIBUS-DP module is used exclusively as an MPI slave, only the green Power LED is on.