Configuring Hardware and Communication Connections STEP 7.pdf

Point-to-Point Connection
Configuring Connections
The local CP 441 provides the link for the connection between an S7-400 CPU and
a communication partner connected via a point-to-point connection. On the CP, a
conversion is made to the addressing mechanisms of the selected transfer
procedure. For this reason, the point-to-point connection ends in the CP 441 and
not at the communication partner as for other connection types.
The number of connections to the CP depends on the set procedure.
FMS Connection
PROFIBUS FMS (Field bus Message Specification) has the following features:
• For the transfer of structured data (FMS variables)
• Fulfills the European standard EN 50170 Vol.2 PROFIBUS
• For open communication with non-Siemens devices on PROFIBUS
• Application on the remote communication partner acknowledges receipt of the
data
• Can be ordered in layer 7 of the ISO reference model
• FMS services are provided on the PC as C functions
FDL Connection
PROFIBUS FDL (Field bus Data Link) has the following features:
• For the transfer of data to a communication partner (for example, SIMATIC S5
or PC) that supports sending and receiving in accordance with the SDA function
(Send Data with Acknowledge)
• The receipt of data is confirmed by the FDL service of the communication
partner with an acknowledgement
• For PROFIBUS subnets only
• Fulfills the European standard EN 50170 Vol.2 PROFIBUS
• Can be ordered in layer 2 of the ISO reference model
• FDL services are provided on the PC as C functions
Configuring Hardware and Communication Connections with STEP 7
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