Funk-Electronic Piciorgros GmbH
RTU-810
V2.30 - Page 59 of 126
Handshake
control
The CTS output of the RTU-810 is always operated, regardless if it's needed/connected
in the application or not. These settings are available
for RS-232 type interfaces
:
CTS: No incoming handshake, the CTS output is operating (but must not be
connected if not required by the connected equipment)
CTS/RTS: The output of the serial interface can be paused by the RTS input.
Use this option with care, if the interface is put on hold for a too long time
incoming data for this interface can time out and get lost in the internal buffers
of the RTU-810!
CTS line simulates DCD: Some older RTU equipment may need a DCD signal
which is activated before any data is transmitted to the equipment and which is
deactivated after the transmission.
To connect these kind of equipment, the CTS output of the RTU-810 can be
used to simulate this DCD behavior.
If this option is selected and applied, two additional fields will appear on the
page to set the time between activation and data output and between end of
data and the deactivation.
If the interface is a RS-422/485 interface on the COM port, a selection between RS-485
and RS-422 mode is presented instead:
Mode
Timeout: This is the default and the setting for fully transparent
communication. Once the first character is received on the interface, a timer is
set counting down milliseconds.
With each character which is received before this timer runs out, the character
is added to a buffer and the timer is reset to its initial value.
Once no character is received and the timer runs down to 0, the buffered data is
treated as a complete data telegram and will be processed by the RTU-810.
CR/LF: Received bytes are collected in the input buffer until a "CR" is
received. The "CR" is not added to the data and the buffer will be processed
after the reception of the "CR" character.
Trailing "LF" characters are ignored.
Any transmitted data on the interface will end with "CRLF".
3964R: Local point-to-point protocol for serial lines, mostly used by Siemens
PLC's.
Timeout
In case the "Timeout" mode is selected, this gives the number of milliseconds for the
timer. Once a gap of more than this time appears after a received character, the reception
is treated as complete and the buffer will be processed by the RTU-810.
The default is 10 times of a complete character with the selected baud rate. If the baud
rate is changed, the timeout value will be automatically recalculated by the RTU-810 to
meet the 10-characters-default.
The timeout can also be modified manually. This may be necessary if a slow SCADA
PC is connected which sometimes delays the data flow on its interface due to task
switching. In this case a value of 50ms @ 9600 bit/s is sufficient in most cases.
