User`s guide

4-4
Programming over RS-232-C
Minimum Three-Wire Interface with Software Protocol
Minimum Three-Wire Interface with Software Protocol
With a three-wire interface, the software (as compared to interface hardware)
controls the data flow between the oscilloscope and the controller. This provides
a much simpler connection between devices because you can ignore hardware
handshake requirements. The oscilloscope uses the following connections on
its RS-232-C interface for three-wire communication:
• Pin 7 SGND (Signal Ground)
• Pin 2 TD (Transmit Data from oscilloscope)
• Pin 3 RD (Receive Data into oscilloscope)
The TD (Transmit Data) line from the oscilloscope must connect to the RD
(Receive Data) line on the controller. Likewise, the RD line from the
oscilloscope must connect to the TD line on the controller. Internal pull-up
resistors in the oscilloscope ensure the DCD, DSR, and CTS lines remain high
when you are using a three-wire interface.
No Hardware Means to Control Data Flow
The three-wire interface provides no hardware means to control data flow between
the controller and the oscilloscope. XON/OFF protocol is the only means to control
this data flow.