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shielded.
Setup
To use the IEEE-488 interface connect an IEEE-488 standard cable to the back of the
bath, set the device address, and set the transmission termination character.
To enter the IEEE-488 parameter menu, press "EXIT" while holding down "SET", then
release both buttons to enter the secondary menu. Press "SET" repeatedly until the
display reaches "PrObe". Press "UP" repeatedly until the IEEE-488 interface menu is
indicated with "IEEE". Press "SET" to enter the IEEE-488 parameter menu.
IEEE-488 Address
The IEEE-488 address is indicated with "AddreSS". Press "SET" to program the
address. The default address is 22. Change the device address of the bath if necessary to
match the address used by the communication equipment by pressing "UP" or "DOWN" .
Press "SET" to save the new setting or "EXIT" to abort and skip to the next parameter.
Transmission Termination
The IEEE-488 transmission termination is indicated with "EOS". Press "SET" to access
the termination character. The present setting is displayed. Press "UP" or "DOWN" to
change the setting. Press "SET" to save the new setting or "EXIT" to abort and skip to
the next parameter.
IEEE-488 Operation
Commands may now be sent via the IEEE-488 interface to read or set the temperature or
access other controller functions. All commands are ASCII character strings and are
terminated with a carriage-return (CR, ASCII 13). Interface commands are listed below.
Interface Commands
The various commands for accessing the bath controller functions via the digital
interfaces are listed in this section (see Table 10-1). These commands are used with both
the RS-232 serial interface and the IEEE-488 GPIB interface. In either case the
commands are terminated with a carriage-return character. The interface makes no
distinction between upper and lower case letters, hence either may be used. Commands
may be abbreviated to the minimum number of letters, which determines a unique
command. A command may be used to either set a parameter or display a parameter
depending on whether or not a value is sent with the command following a "=" character.
For example an "s" <cr> returns the current set-point and an "s=50.00" <cr> sets the set-
point to 50.00 degrees.
In the list of commands, characters or data within brackets, "[" and "]", are optional for
the command. A slash, "/", denotes alternate characters or data. Numeric data, denoted by
"n", may be entered in decimal or exponential notation. Characters are shown in lower
case although upper case may be used. Spaces may be added within command strings and
will simply be ignored. Backspace (BS, ASCII 8) may be used to erase the previous
character. A terminating CR is implied with all commands.
Cooling Control
The 7341 bath has a fully automated refrigeration control system when the cooling power
switch on the front panel is activated. Under normal conditions, the refrigeration is on at
any temperature below approximately 60°C (see Refrigeration in Chapter 8). When the
bath is controlling at temperatures between 0°C and 60°C, the refrigeration is in the hot
gas bypass or reduced cooling mode. Below 0°C the refrigeration is in the high cooling
mode and the hot gas bypass is turned off automatically. When the bath is cooling from
one temperature to another below 60°C, cooling is at maximum until the bath is within 1
degree C of the set-point. These conditions are the default conditions but may be altered
Digital Communication Interface
Interface Commands
10
10-5
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Troubleshooting
