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IM CW140-E
15-4
15.3 Handshake Methods
For the CW140 power meter to be able to communicate with a personal
computer through the RS-232C interface, the equipment on both sides must
agree on a set of rules and go through a series of procedures relating to
electrical signals to ensure reliable data exchange. This series of procedures
is called a handshake. Because there are many handshake methods that can
be used in combination with a computer, it is essential that the same method
is chosen for the meter and the computer.
You can choose from any of the four methods shown in the following table.
Data Sending Control
(Control of sending data to a computer)
Data Receiving Control
(Control of receiving data from a computer)
Software
Handshake
Software
Handshake
Handshake Methods (
䊊
means it is a valid selection)
O F F / O F F
X O N / X O N
X O N / R S
C S / R S
Handshake method Stops sending
when X-OFF is
received.
Resumes when
X-ON is
received.
Stops sending
when CB
(CTS) is false.
Resumes
when it is true.
No
handshake
No
handshake
Hardware
Handshake
Hardware
Handshake
Sends X-OFF
when receive
data buffer is 3/4
full.
Sends X-ON
when receive
data buffer is 1/4
full.
Sets CA (RTS)
to False when
receive data
buffer is 3/4 full.
Sets to True
when receive
data buffer is
1/4 full.
OFF-OFF
●
Send Data Control
There is no handshake between the meter and the computer. The "X-OFF"
and "X-ON" signals are treated as data, and CS is ignored.
●
Receive Data Control
There is no handshake between the meter and the computer. When the
receive buffer is full, all extra data are discarded.
RS is fixed to true.
Содержание CW140
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