Specifications

Operating Manual SEFRAM 4451
M4451 A00
64
4.15.1 General
The INSTALLATION section of this manual describes the RS-232-C connection for the instrument. Be
sure that you have the Remote Mode set to RS-232 and correctly set the baud rate.
EIA standard RS-232-C specifies the electrical characteristics and pin out of a serial communication
standard for connecting "data terminal equipment" (DTE) to "data communication equipment" (DCE).
Data terminal equipment is usually devices such as terminals, computers, or printers that are the final
destination for data. Data communication equipment, on the other hand, is usually a modem or other device
that converts the data to another form and passes it through. The instrument can be configured only as a
DCE, so in most cases it can be connected with a straight-through cable to a computer, but would require
special cabling to connect to another DCE device.
The baud rate is the bit rate during the transmission of a word in bits per second. Different devices use
many baud rates, but the baud rates of the two devices that are connected must be the same. The instrument
can be set to different baud rates ranging from 1200 to 115,000 as described in Section 3, Operating
Instructions.
Data signals over the RS-232-C use a voltage of +3V to +25V to represent a zero (called a space) and a
voltage of -3V to -25V to represent a one (called a mark). Handshake and control lines use +3V to +25V to
indicate a true condition and -3V to -25V to indicate a false condition.
When no data is being transmitted, the idle state of the data lines will be the mark state. To transmit a byte,
the transmitting device first sends a start bit to synchronize the receiver.
4.15.2 RS-232-C Operation
The RS-232-C standard is not very specific about many of the handshaking signals and it is therefore
usually necessary to refer to the manuals for both of the devices being connected to determine the exact pin
out, signal definition, and signal direction for the devices.
The serial interface implements the same SCPI command set as the GPIB interface. The instrument is
programmed by sending ASCII coded characters to the instrument.
When the instrument is in the remote mode remote command input has priority over any front panel
control. Therefore, as long as the serial interface is continuously supplied with data, the keyboard will
appear to be inoperative to the user.