Siemens Simatic S7-200 System Manual page 170

Network Communications and the S7-200 CPU
Configurations Using a PC with an MPI or CP Card: Multiple-Master Network
Many configurations are possible when you use a multipoint interface card or
communications processor card. You can have a station running the STEP 7-Micro/WIN
programming software (PC with MPI or CP card, or a SIMATIC programming device)
connected to a network that includes several master devices. (This is also true of the PC/PPI
cable if you have enabled multiple masters.) These master devices include operator panels
and text displays (TD 200 units). Figure 9-8 shows a configuration with two TD 200 units
added to the network.
In this configuration, the communication possibilities are listed below:
STEP 7-Micro/WIN (on station 0) can be monitoring the status on programming station 2,
while the TD 200 units (stations 5 and 1) communicate with the CPU 214 modules
(stations 3 and 4, respectively).
Both CPU 214 modules can be enabled to send messages by using network instructions
(NETR and NETW).
Station 3 can read data from and write data to station 2 (CPU 212) and station 4
(CPU 214).
Station 4 can read data from and write data to station 2 (CPU 212) and station 3
(CPU 214).
It is possible to connect many master and slave stations to the same network. However, the
performance of the network can be adversely affected as more stations are added.
Station 0
Apply termination and bias at stations 2 and 4. These stations are at the extreme ends of the network.
The connectors used at stations 2, 3 and 4 have a programming port connector.
Figure 9-8
9-14
CPU 212 CPU 214
Station 2 Station 3
MPI cable
(RS-485)
Using an MPI or CP Card to Communicate with S7-200 CPUs
CPU 214 TD 200
Station 4 Station 1
S7-200 Programmable Controller System Manual
C79000-G7076-C230-02
TD 200
Station 5