Tektronix CMD 80, User Manual

Page: 362 / 672

Appendix D: Remote Control
D–6
CMD 80 Digital Radiocommunication Tester User Manual
Software Handshake. In the case of the software handshake, the data transfer is
controlled using the two control characters XON and XOFF.
The tester uses the control character XON to indicate that it is ready to receive
data. If the receive buffer is full, it sends the XOFF character via the interface to
the controller. The controller then interrupts the data output until it receives
another XON from the CMD. The controller indicates to the tester that it is ready
to receive data in the same way.
Cable for Local Controller Coupling in the Case of Software Handshake. The
connection of the tester with the controller in the case of software handshake is
effected by crossing the data lines. The wiring diagram shown in Figure D–3
applies to a controller with 9-pin or 25-pin configuration.
1
2
3
4
5
6
7
8
9 1
3
2
6
5
4
8
7
9
1
2
3
4
5
6
7
8
9 8
2
3
6
7
20
5
4
22
CMD
9-pin
Controller
9-pin
CMD
9-pin
Controller
25-pin
RxD / TxD
TxD / RxD
GND / GND
RxD / TxD
TxD / RxD
GND / GND
Figure D–3: Wiring of the data lines for software handshake
Hardware Handshake. In the case of the hardware handshake, the tester indicates
that it is ready to receive data via the lines DTR and RTS. A logic 0 on both lines
means “ready” and a logic 1 means “not ready”. The RTS line is always active
(logic 0) as long as the serial interface is switched on. The DTR line thus
controls the readiness of the tester to receive data.
The readiness of the remote station to receive data is reported to the tester via the
CTS and DSR lines. A logic 0 on both lines activates the data output and a logic
Handshake