Chapter 6, COMPUTER OPERATION
6-34
bit number bit negated bit asserted
0 data = 7 bits data = 8 bits
1 no parity bit 1 parity bit
2 even parity odd parity
3 echo disabled echo enabled
4 prompt disabled prompt enabled
RSADDR [n] Set/read RS232 address
The value of n sets the RS232 address in the range 0 to 15. This is relevant only
when using more than one instrument connected via the RS232 “daisy-chain”
method. Each instrument must be set to a unique address.
USBTERM [n] Set/read USB terminator
The value of n sets the USB terminator according to the following table:
n Function
0 A null character (ASCII 0)
1 A null character (ASCII 0), followed by a byte representing the value of the
status Byte (table 6-1), followed by a byte representing the value of the Overload
Byte (table 6-1)
\N n Address command
When the model 7270 is daisy-chained with other compatible instruments this
command will change which instrument is addressed. All daisy-chained instruments
receive commands but only the currently addressed instrument will implement or
respond to the commands. The exception is the \N n command. If n matches the
address set from the front panel the instrument will switch into addressed mode. If n
does not match the address set from the front panel the instrument will switch into
unaddressed mode. Note that the \N n command does not change the address of an
instrument but which instrument is addressed.
NOTE: All instruments must have a unique address.
DD [n] Define delimiter control
The value of n, which can be set to 13 or from 32 to 125, determines the ASCII value
of the character sent by the lock-in amplifier to separate two numeric values in a
two-value response, such as that generated by the MP (magnitude and phase)
command.
ST Report status byte
Causes the lock-in amplifier to respond with the status byte, an integer between 0
and 255, which is the decimal equivalent of a binary number with the following bit-
significance:
Bit 0 Command complete
Bit 1 Invalid command
Bit 2 Command parameter error
Bit 3 Reference unlock
Bit 4 Output overload - read overload byte to determine location
Bit 5 New ADC values available after external trigger
Bit 6 Input overload
Bit 7 Data available
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