Overview of the RS-232C Interface
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IM 767361-01E
Overview of the RS-232 Interface
Description of Each Handshaking Method
OFF-OFF
• Data Sending Control
Handshaking is not carried out between the instrument and the PC. X-on and
X-off messages from the PC are treated as data, and CB(CTS) is ignored.
• Data Receiving Control
Handshaking is not carried out between the instrument and the PC. After
the instrument’s receive buffer becomes FULL, excess data is discarded.
Therefore, in order to prevent both the instrument’s and the PC’s receive
buffers from becoming FULL, you should create a program on the PC.
CA(RTS) is fixed at True.
XON-XON
• Data Sending Control
Software handshaking is carried out between the instrument and the PC. If
the instrument receives the X-off code from the PC while the instrument is
transmitting data, the transmission is stopped until the X-on code is received.
CB(CTS) messages from the PC are ignored.
• Data Receiving Control
Software handshaking is carried out between the instrument and the PC.
When the instrument’s available buffer space reaches 64 bytes it transmits an
X-off code to the PC, and when the buffer space reaches 192 bytes an X-on
code is sent. CA(RTS) is fixed at True.
XON-RTS
• Data Sending Control
Software handshaking is carried out between the instrument and the PC. If
the instrument receives the X-off code from the PC while the instrument is
transmitting data, the transmission is stopped until the X-on code is received.
CB(CTS) messages from the PC are ignored.
• Data receiving control
Hardware handshaking is carried out between the instrument and the PC.
When the instrument’s receive buffer reaches 64 bytes CA(RTS) is set to
False, and when the buffer reaches 192 bytes CA(RTS) is set to True.
CTS-RTS
• Data Sending Control
Hardware handshaking is carried out between the instrument and the PC.
If CB(CTS) becomes False while the instrument is transmitting data, the
transmission is stopped until CB(CTS) becomes True again. X-on and X-off
messages from the PC are treated as data.
• Data Receiving Control
Hardware handshaking is carried out between the instrument and the PC.
When the instrument’s receive buffer reaches 64 bytes, CA(RTS) is set to
False, and when the buffer reaches 192 bytes CA(RTS) is set to True.