Siemens Simatic S7-200 System Manual page 392

S7-200 Programmable Controller System Manual
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-41 summarizes the status indications signified by the EM 277 status LEDs.
Table A-41
LED
CPU FAULT
POWER
DP ERROR
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-24 for one possible network configuration.
A
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.
380
EM 277 PROFIBUS–DP Module Status LEDs
OFF RED
Module is good Internal Module Failure
No 24 VDC User Power ––
Left Data Exchange
No Error
Mode
Not in Data Exchange Mode ––
FLASHING RED GREEN
–– ––
–– 24 VDC User Power Good
Parameterization/
––
Configuration Error
–– In Data Exchange Mode