36
SME1202A
6)
Remote Control
6.1
RS232C Connection
RS-232 standard, also called as asynchronous serial communication standard, has
already been widely used for data communication between computers, computer and
external equipment. RS is the English abbreviation of Recommended Standard; 232, the
standard number. This standard is issued by EIA in 1969, which rules to send one bit in a
data line every time.
As most serial interfaces, the serial interface of SME1202A is also not strictly based on
RS-232 standard but only uses the smallest subset of this standard. The signals are listed
in the following table.
Table 6-1 RS-232 Signal and Pin Connector
The reason is that the use of three lines is much more inexpensive and much simpler
than that of five lines or six lines, which is the biggest advantage of using serial interface
for communication.
The connection of the instrument with PC is shown in figure 6-1.
TXD(2) (3) RXD
PC
（
Controller
）
RXD(3) (2) TXD SME1202A
GND(5) (5) GND
Figure 6-1 Connection of the instrument with PC
Figure 6-1 shows that the serial interface pin definition of this instrument is different from
that of 9 pin connector used in the computer. RS232 interface characterizes with a baud
rate ranging from 9600 to 115200, no parity, 8-bit data, 1- stop bit stop.
The instrument commands comply with the SCPI standard. When a command string is
transmitted to the instrument, it is required to send LF (hexadecimal: 0AH) as the
terminating character. Each time the maximum receivable number of SPCI command
string is 2kByte.
For result data formats transmitted to a PC from the instrument, see Commands
Reference.
Signal
Code
Connector Pin Number
Transmitted Data
TXD
2
Received Data
RXD
3
Signal Ground Common
GND
5
