Specifications

S7-200 Programmable Controller System Manual
442
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 turn s 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-43 summarizes the status indications signified by the EM 277 status LEDs.
Table A-43 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.
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.