Lenze I/O system 1000 System Manual - Manual (Page 727)

Appendix
Serial process interfacing
15
l
727 EDSIO1000 EN 7.0
15 Appendix
15.1 Serial process interfacing
With the EPM−S640 and EPM−S650 I/O compound modules a serial process interfacing to
different target or source systems can be implemented.
EPM−S640: Serial process interfacing via RS232 interface
EPM−S650: Serial process interfacing via RS422 or RS485 interface
Serial transmission of a character
The point−to−point coupling between two communication partners is the simplest form of
the exchange of information. The EPM−S640 I/O compound module provides the interface
between a higher−level system (control) and a serially connected communication partner.
In the case of serial data transmission, the individual bits of a byte of a piece of information
to be transmitted are transferred successively in a defined sequence.
Character frame
The bidirectional data exchange makes a distinction between half duplex and full duplex
operation. In half duplex operation, data are either sent or received at a certain time. A
simultaneous data exchange can only be effected in full duplex operation.
Each character to be transmitted is preceded by a synchronisation pulse as start bit. The
end of the character transfer is set by the stop bit. In addition to the start and stop bit,
further parameterisable agreements between the communication partners are required
for a serial data transmission.
This character frame consists of the following elements:
ƒ Transmission speed (baud rate)
ƒ Character delay time and acknowledgement time
ƒ Parity
ƒ Number of data bits
ƒ Number of stop bits