VIPA CP 341S, Manual

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Chapter 5 Communication protocols
Manual VIPA System 300S SPEED7
5-6 HB140E - CP - RE_341-2CH71 - Rev. 09/46
STX/ETX
STX/ETX is a simple protocol employing headers and trailers. The
STX/ETX procedure is suitable for the transfer of ASCII characters
(20h…7Fh). It does not use block checks. Any data transferred from the
periphery must be preceded by an STX (Start of Text) followed by the data
characters. An ETX (End of Text) must be inserted as the terminating
character.
The effective data, which includes all the characters between STX and
ETX, are transferred to the CPU when the ETX has been received.
When data is sent from the CPU to a peripheral device, any user data is
handed to the CP where it is enclosed with an STX start character and an
ETX termination character and transferred to the communication partner.
Message structure:
STX2 Z1 Z2 Zn ETX1 ETX2
ZVZ
STX1
You may define up to 2 start and end characters. It is also possible to
specify a ZNA for the sending station.
For the deployment of the STX/ETX protocol you have to add to your
master system a SPEED-Bus slave and to configure a CP 341-
2CH71(STX/ETX) as described at "Hardware configuration".
The properties dialog of the CP may be opened by a double-click. Every
parameter of the STX/ETX protocol may be accessed via the register
Parameter Assignment
with
Device-specific parameters
.
Related to the interface the interface number COM1 respectively COM2 is
put in front of the parameter designation.
Here the transfer speed in bit/s may be selected from a selection list.
Range of values: 150 ... 115200
Default: 9600
Leave this value preset to "STX/ETX". If "No protocol" is set, the interface
is deactivated and on a send job you will get an according error message.
Range of values: No protocol, STX/ETX
Default: ASCII
Mode of operation
Proceeding
STX/ETX
parameters
Transmission rate
Protocol