• "Class E" addresses: 240.0.0.0 - 247.255.255.255

• Broadcast addresses: e.g. 255.255.255.255

4.2.2 Subnet mask

If a subnet mask is specified during configuration, its structure must comply with

the general conventions defining subnet mask validity.

Please note that the validity of an IP address and an associated subnet mask are

interdependent.

4.2.3 TSAPs

The TSAPs consist of 2 bytes. The first byte specifies the connection and the second

byte is composed of the rack number and the position of the communications

module. The following value ranges apply for the first byte.

• Local TSAP value range: 16#02, 16#10 - 16#FE

• Remote TSAP value range: 16#02, 16#03, 16#10 - 16#FE

The structure of the second byte is not checked by the CP 243-1.

Defining the address of the control byte and the number of connections

Use the next dialog to specify the address of the byte in the memory address

space of your S7-200 system from which the CP 243-1 can be addressed from the

S7-200 CPU. This address depends on the position of the CP 243-1 in your

S7-200 system and on the number of outputs in your S7-200 system. If, when you

began configuring the system, you had the Ethernet Wizard determine the position

of the CP 243-1 in your S7-200 system, the Wizard will now provide you with the

address to be used.

Basically, you can determine the memory address spaces occupied by the modules

present in your S7-200 system by enabling the "Information..." entry in the

"PLC" menu in STEP 7 Micro/WIN 32. In this manner you will also find the address

under which your CP 243-1 can be addressed in your S7-200 system.

In this dialog, you can also define the maximum number of connections your

CP 243-1 should maintain in parallel at any one time. Up to 8 such connections can

be maintained. A dialog in which you can configure the connection then appears

for each connection you specify here.

Configuring the inpidual connections

The connections that you established in the previous dialog are configured in the

dialogs that follow. For each connection, you must first define whether your S7-200

system should be operated as a client or server. This will determine the structure of

the dialog.

If your S7-200 system is to be operated on the connection as a client, then you

must specify the address of the communication partner and the communications

end point ("TSAP") in this partner. Moreover, in an additional dialog, you must

specify which data is to be exchanged between your S7-200 system and the specified

communication partner. At this point you also define whether these data is to

be read or written. Up to 32 read/write commands can be defined per connection.

If your S7-200 system is operated on the connection as a server, then you can define

to which communication partner you wish to grant access to your system by

assigning an IP address. However, you can also set each server so that it always

grants access from any IP address. You must also define the communications end

point ("TSAP") in your communication partner from which you grant access to your

S7-200 system.

A Keep Alive system can be enabled for both client and server connections.

Please use the communications end points ("TSAPs") of your communication partner

specified in the configuration of that partner. In an S7-200 system, it is generated

using STEP 7 Micro/WIN 32. In an S7-300, S7-400 or OPC-based system,

use STEP 7 to do so (see also Chapter 4.4).

Note