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Chapter 6, COMPUTER OPERATION
RSADDR [n]
USBTERM [n]
\N n
DD [n]
ST
6-34
bit number bit negated
0
data = 7 bits
1
no parity bit
2
even parity
3
echo disabled
4
prompt disabled
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.
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)
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.
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.
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
bit asserted
data = 8 bits
1 parity bit
odd parity
echo enabled
prompt enabled
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