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ötz • Telefon 03641/66880 • Fax 03641/668866 • www.piezojena.com
83
sketch 6: triangle scan with trigger impulses at the rising edge
8.9 data recorder
For deeper analysis of the system behavior, a two channel data recorder can be used.
Channel 1 records the position signal, channel 2 the actuator voltage. The maximum record length
is 500000 samples each channel. Both channels always have the same record length, given by the
command “reclen,value” [value=0..500000]. For slow or moderate movements, it is possible to
reduce the maximum sample rate of 50kHz, by just recording every n
th
value. This can be done
with the command “recstride,N” [N=1..1000]. The recording duration is given by
reclen.
recstride
20
rectlen
µs
t
t
There are several ways to start the data recorder:
the “set”-command; a running recording will be aborted and a new one will started
the start
of wave generator (command “gfkt,n” , n>0)
the start of scan function (command “ss,1”)
the command “recstart” (also without performing any movement)
The recording ends automatically after reaching the desired record length (reclen). The readout
can be done independent from recording, also while recording.
Readout the data recorder:
To readout the data recorder, the commands „m“ (position value) and „u“ (actuator voltage) are
used. The readout can start at any recorded position, the pointer to the start address can be set
with „recrdptr,n“ [n=0..499999]. After this, the readout of the recorded position value or actuator
voltage value by commands “m” or “u” can be executed. The address pointer will be automatically
increased, so that a further command returns the next recorded value. This pointer increase effects
both channels. Thus, to read out the same index of both channels the initial pointer value has to be
set again.
There are different readout modes. When the commands “m” or “u” are sent without a parameter or
with parameter=0, the answer is formatted to “command,value<CR>”, when the commands are
sent with parameter=1, the answer is formatted to “value<CR>”. By appending a further parameter
value=n, the device responds a block of n values (see examples at the end of this chapter).
Output data format
To reduce the amount of transmitted data, a data reduced transfer with a constant data length is
realized.
Counts with value range from 0 to 0xffff (16bit, hexadecimal format) will be transmitted. These
counts represent a range for the position value from -30% to 130%, where 0%..100% corresponds
to the closed-loop-range of the actuator and an overshoot of +/- 30% is representable.
