Siemens SIMATIC S7-200 System Manual page 459

LED Status Indicators for the EM 277 PROFIBUS- - DP
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
-
communications are not attempted.
Once DP communications have 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 communications are 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-45 summarizes the status indications signified by the EM 277 status LEDs.
Table A-45 EM 277 PROFIBUS- -DP Module Status LEDs
LED
Module is good
CPU FAULT
No 24 VDC User Power
POWER
DP ERROR No Error
Not in Data Exchange Mode
DX MODE
Note: When the EM 277 PROFIBUS--DP module is used exclusively as an MPI slave, only the green Power LED is on.
Additional Configuration Features
The EM 277 PROFIBUS--DP module can be used as a communications interface to other MPI
masters, whether or not it is being used as a PROFIBUS--DP slave. The module can provide a
connection from the S7-300/400 to the S7-200 using the XGET/XPUT functions of the
S7-300/400. STEP 7--Micro/WIN and a network card (such as the CP5611) using the MPI or
PROFIBUS parameter set, an OP device or the TD 200 (Rel. 2.0 or greater, order number 6ES7
272--0AA20--0YA0) can be used to communicate with the S7-200 through the EM 277
PROFIBUS--DP module.
A maximum of six connections (six devices) in addition to the DP master can be connected to the
EM 277 PROFIBUS--DP module. One connection is reserved for a programming device (PG) and
one is reserved for an operator panel (OP). The other four connections can be used by any MPI
master. In order for the EM 277 PROFIBUS--DP module to communicate with multiple masters, all
masters must be operating at the same baud rate. See the Figure A-30 for one possible network
configuration.
When the EM 277 PROFIBUS--DP module is used for MPI communications, the MPI master must
use the station address of the module for all messages that are sent to the S7-200 to which the
module is connected. MPI messages sent to the EM 277 PROFIBUS--DP module are passed on
to the S7-200.
The EM 277 PROFIBUS--DP module is a slave module and cannot be used for communications
between S7-200 PLCs using the NETR and NETW functions. The EM 277 PROFIBUS--DP
module cannot be used for Freeport communications.
OFF RED
Internal Module
Failure
----
Left Data Exchange
Mode
----
Technical Specifications
FLASHING RED
---- ----
---- 24 VDC User Power
Good
Parameterization/
----
Configuration Error
---- In Data Exchange
Mode
Appendix A
GREEN
445