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Chapter 3 Front-Panel Operation
RS-232 Interface Configuration
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When the power supply wants to “talk” over the interface (which means that
it has processed a query) and has received a <
new line> message
terminator, it will set the DTR line FALSE. This implies that once a query has
been sent to the power supply, the bus controller should read the response
before attempting to send more data. It also means that a <
new line> must
terminate the command string. After the response has been output, the
power supply sets the DTR line TRUE again, unless the first case (see
above) prevents this.
The power supply monitors the DSR line to determine when the bus
controller is ready to accept data over the interface. The power supply
monitors the DSR line (pin 6 on the RS-232 connector) before each
character is sent. The output is suspended if the DSR line is FALSE. When
the DSR line goes TRUE, transmission will resume.
The power supply holds the DTR line FALSE while output is suspended. A
form of interface
deadlock exists until the bus controller asserts the DSR
line TRUE to allow the power supply to complete the transmission. You can
break the interface deadlock by sending the <
Ctrl-C> character, which
clears the operation in progress and discards pending output (this is
equivalent to the IEEE-488 device clear action).
For the <Ctrl-C> character to be recognized reliably by the power supply
while it holds DTR FALSE, the bus controller must first set DSR FALSE.
RS-232 Troubleshooting
Here are a few things to check if you are having problems communicating
over the RS-232 interface. If you need additional help, refer to the
documentation that came with your computer.
• Verify that the power supply and your computer are configured for the
same baud rate, parity, and number of data bits. Make sure that your
computer is set up for
1 start bit and 2 stop bits (these values are fixed
on the power supply).
• Make sure to execute the
SYSTem:REMote
command to place the
power supply in the remote mode.
• Verify that you have connected the correct interface cable and adapters.
Even if the cable has the proper connectors for your system, the internal
wiring may be incorrect.
The
Agilent 34398A Cable Kit
can be used to
connect the power supply to most computers or terminals.
• Verify that you have connected the interface cable to the correct serial
port on your computer (COM1, COM2, etc.).