Ametek 7280 Instruction Manual page 206

Appendix F, ALPHABETICAL LISTING OF COMMANDS
OA[.] [n]
OF[.] [n]
PHA[.]
PORTDIR [n]
READBYTE
F-14
12 dB/octave if it had previously been 18 or 24 dB/octave.
Oscillator amplitude control
In fixed point mode n sets the oscillator amplitude in mV. The range of n is 0 to 1000
representing 0 to 1 V rms.
In floating point mode n sets the amplitude in volts.
Oscillator frequency control
In fixed point mode n sets the oscillator frequency in mHz. The range of n is 0 to
2,000,000,000 representing 0 to 2.000 MHz.
In floating point mode n sets the oscillator frequency in Hz. The range of n is 0 to
2.0E6
Signal phase
In fixed point mode causes the lock-in amplifier to respond with the signal phase in
centidegrees, in the range ±18000.
In floating point mode causes the lock-in amplifier to respond with the signal phase
in degrees.
Digital port direction control
The value of n determines which of the eight lines on the digital port are configured
as inputs and which as outputs. The parameter n is a decimal number whose bit-wise
interpretation defines whether the corresponding line is an input or output. The line is
an input if the corresponding bit is a "1". For example:
n status
0 All lines configured as inputs
1 D0 = output, D1 - D7 = inputs
2 D1 = output, D0 and D2 - D7 = inputs
4 D2 = output, D0 - D1 and D3 - D7 = inputs
8 D3 = output, D0 - D2 and D4 - D7 = inputs
16 D4 = output, D0 - D3 and D5 - D7 = inputs
32 D5 = output, D0 - D4 and D6 - D7 = inputs
64 D6 = output, D0 - D5 and D7 = inputs
128 D7 = output, D0 - D6 inputs
255 All lines configured as outputs
Read digital port input
The response to the READBYTE command is an integer between 0 and 255
representing the binary value of all eight lines of the rear panel digital port. Hence,
for example, if PORTDIR = 0 and the response to READBYTE is 255, then all lines
are high, and if the response to READBYTE is 0, then all lines are low. Note that
because the command does not differentiate between whether a line is configured as
an input or output, it can be used as a single command to determine the present status
of all eight lines, both inputs and outputs, of the port.