Phytec miniMODUL-537, Hardware Manual

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The Serial Interface
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PHYTEC Meßtechnik GmbH 1993 L-006e_2
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6.5.3 The Pin Assignment of the Interface for the
miniMODUL-537
For better recognition of the interface connections with RS-232
standard the data-in/outputs are emphasized at the print of the circuit
board. The arrows indicate the direction of data-flow. The connections
of the RS-485 interface are also emphasized at the print of the
circuit board.
6.6 General Remarks for RS-232 and RS-485 Interfaces
6.6.1 RS-232 Interface
The serial data transfer with RS-232 standard is only appropriate for
the connection of two participants via relative short distances of a
about 10m. The baud rate, that can be employed depends very much
on the length and type of the connection cable. Standard baud rates for
the communication are 9600 and 19200 baud for interoffice
applications. The transmission of data in one direction require one line
(RxD, TxD). In addition to GND also control lines might be used,
which influence the flow of data. All PHYTEC-controller boards use
RS-232 interfaces without control lines. The mutual overflow control
is achieved by software-handshaking. For the XON-XOFF protocol
the reserved signs 11H and 13H are added in the data-flow for control
purposes. This requires, that the handling of the protocol of the par-
ticipants is adapted to each other. Otherwise transmission errors, loss
of characters or locking might occur. Therefore we recommend the
application of our communication software. Because of this protocol,
only ASCII-coded signs and a restricted number of character sets can
be transmitted.