Operating instructions

R&S ESCI Instrument Interfaces
1166.6004.12 8.9 E-1
Control Characters
For interface control, several strings are defined and control characters are reserved which are based
upon IEC Bus control.
Table 8-5 Control strings or control characters of the RS-232 interface
Control string or character Function
'@REM' Switch over to remote
'@LOC' Switch over to local
'@SRQ' Service Request SRQ ( SRQ is sent by the instrument)
'@GET' Group Execute Trigger (GET)
'@DCL' Reset instrument (Device Clear DCL)
<Ctrl Q> 11 Hex Enables character output / XON
<Ctrl S> 13 Hex Inhibits character output / XOFF
0D Hex, 0A Hex Terminator <CR>, <LF>
Handshake
Software handshake
In the software handshake mode of operation, the data transfer is controlled using the two control
characters XON / XOFF.
The instrument 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 instrument. The controller indicates to the
instrument that it is ready to receive data in the same way.
Cable required for software handshake
The connection of the instrument with a controller for software handshake is made by crossing the data
lines. The following wiring diagram applies to a controller with a 9-pin or 25-pin configuration.
Instrument Controller Instrument Controller
9-pin 9-pin 9-pin 25-pin
1
2
3
4
5
6
7
8
9
------------RxD / TxD---------------
------------TxD / RxD---------------
------------GND / GND-------------
1
3
2
6
5
4
8
7
9
1
2
3
4
5
6
7
8
9
------------RxD / TxD---------------
------------TxD / RxD---------------
------------GND / GND-------------
8
2
3
6
7
20
5
4
22
Fig. 8-6 Wiring of the data lines for software handshake