Lake Shore 480, Руководство пользователя, Страница: 80 / 132

Lake Shore Model 480 Fluxmeter User’s Manual
6-14 Computer Interface Operation
6.2 SERIAL I/O INTERFACE
RS-232C is a standard of the Electronics Industries Association (EIA) and one of the most common
interfaces between a computer and electronic equipment. The Customer supplied computer must have
a Serial Interface port. The Model 480 Serial Interface complies with the electrical format of the
RS-232C Interface Standard. A Serial Interface between the computer and the Model 480 permits
remote monitoring and control of Model 480 control functions, which in turn controls Model 480
operation. See Figure 6-2.
The Serial Interface can both transmit and receive information. In transmit (Tx) mode, the instrument
converts parallel information to serial and sends it over a cable up to 50 feet long (or longer with proper
shielding). In receive (Rx) mode, the instrument converts serial information back to parallel for
processing.
Refer to Paragraph 6.2.1 for serial interface hardware configuration and adapters, Paragraph 6.2.2 for
serial interface settings, and Paragraph 6.6.3 for a sample BASIC programs to establish
communications between the computer and the Model 480.
The Serial Interface shares Device Specific commands with the IEEE-488 interface listed in Paragraph
6.3. However, without the advantage of the IEEE-488 Architecture, there are several limitations:
• No Bus Control Commands apply.
• Only
Q
IDN? and
Q
RST Common Commands are usable.
• Terminators are fixed to CRLF.
• A query must be added to the end of a command string if the Model 480 must return
information. (Over IEEE-488, the last query response is sent when addressed to talk). For
example: ”UNITS 8;UNITS?” sets the units to gauss and immediately queries unit status.
6.2.1 Serial Interface Hardware Configuration
Below is a technical description of the Serial Interface. Table 6-2 lists communication parameters.
Terminators are fixed to Carriage Return (CR) and Line Feed (LF). The serial interface connector is a
9-Pin D connector.
Table 6-4. Serial Interface Specifications
Transmission
Connector
Timing Format
Transmission Mode
Baud Rate
Bits per Character
Parity Type
Data Interface Levels
Fixed Terminator Three-Wire
9-Pin D Connector
Asynchronous, RS-232C Electrical Format
Half Duplex
300, 1200, or 9600
1 Start, 7 Data, 1 Parity, and 1 Stop
Odd
Transmits and Receives Using EIA Voltage Levels
CR (0DH) LF (0AH)
6.2.2 Serial Interface Settings
To use the Serial Interface, set the Baud rate. Press Baud to display the following screen.
Select­With­°®
Baud­­3­­12­¡96
Press the

or

keys to cycle through the choices of 300, 1200, or 9600 Baud. Press Enter to
accept the new number or Escape to keep the existing setting and return to the normal display.