Lake Shore 475, Руководство пользователя

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Lake Shore Model 475 Gaussmeter User’s Manual
Advanced Operation 5-7
5.3.5 Control Slope Limit
The Model 475 Analog Output 3 (used during control) can be limited to protect the programmable power supply that it
may be driving. Certain power supplies may have a maximum programmable voltage change, and this parameter will
allow those specifications to be met. This parameter is set as volts per minute.
The next control setup screen appears as a prompt for setting the control slope limit.
Ent er f or Cont r ol
L i m +1 . 0 0 0 0 0 V/ mi n
Use the data entry keys to enter a value between 0.01 and 1000. Press Enter to accept the new value and return to the
normal display. Press Escape to restart the setting sequence and enter a new value. Press Escape again to cancel the
sequence and return to the normal display.
5.3.6 Field Control Versus Reading Resolution
To achieve the best speed performance, it is recommended that the field control be used with a DC resolution setting of 3
(refer to Paragraph 4.4.1). The DC resolution setting may be increased during control. This configuration can improve
noise rejection but it is sometimes at the expense of more difficult tuning or even control instability. The additional
filtering creates time lag that destabilizes the control loop. Any control application should be tuned first with a DC
resolution setting of 3. The DC resolution setting should be increased one digit at a time, and then adjustments to P and I
be made (most often P will decrease and I will increase). In most cases, A DC resolution setting of 5 results in a very
slow field control independent of the PI parameters, and makes field control difficult.
5.4 DATALOG
Memory within the instrument provides storage for up to 1024 field readings in a data buffer. The buffer can be filled at
high speed, up to 1000 readings per second. After the data has been filled, the stored readings can then be retrieved over
the interface and processed off-line. The datalog can be started by the external trigger input, the GPIB group execute
trigger (GET) command, or the DLOG command. The datalog sequence will stop after the buffer is filled or the DLOG 0
command is received. Refer to the DLOG command in section 6.3.1. If the datalog sequence is started again the datalog
buffer is reset and all previous data will be lost.
The datalog will store DC field readings in DC mode or RMS readings in RMS or peak mode. When the data is read out
of the buffer, the readings will be in the field units that the instrument is set to. The datalog function will store data at a
rate independent of the reading update rate. Choosing a datalog rate faster than the reading update rate will result in
duplicate readings being stored. Refer to Paragraph 4.6.2 for the DC reading update rate or Paragraph 4.7.4 for the RMS
reading update rate. The table below summarizes the available datalog update rates that can be set using the DLOGSET
command.
DLOGSET setting Datalog update rate
1 1 reading/second
2 10 readings/second
3 30 readings/second
4 100 readings/second
5 200 readings/second
6 400 readings/second
7 800 readings/second
8 1000 readings/second