eDAQ PowerChrom 280, Руководство пользователя

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Chapter 2 — Setting Up 15
The four digital output connections of the Instrument Connection port
provide a means to control external devices. The digital output signals
can be configured as either TTL signal levels or contact closures, by
installing or removing a set of links,
Figure 1–3, page 7 . These digital
outputs can be used to signal external devices such as autosamplers,
fraction collectors, or autoinjectors. More detail on these controls is
provided on
page 16 .
The recording unit uses a universal input switching power supply.
Detector Inputs
Each of the PowerChrom unit’s analog input differential amplifiers have
independently computer-controlled gain from
×
1 (10 V range setting) to
×
5000 (2 mV range setting). Applying more than ±30 V to the detector
inputs could damage the circuitry.
Each input is fitted with a 900 Hz second order Bessel anti-aliasing low-
pass filter which eliminates high frequency interference. Input
impedance is 1 MΩ.
The operation of the input amplifiers is illustrated by the block diagram
in
Figure 2–5 .
Using differential analog inputs for the detectors gives the system
greater immunity to external electrical interference, when used in
conjunction with a suitable cable. The best type of detector cable would
be a twisted pair with a braided shield, as shown in
Figure 2–5 . The
shield should be connected to the detector’s analog ground, or to the
COM pin of CH1 or CH2, but not to both.
Analog Output
The analog output provides a computer–controlled variable output (0 –
10 V, at up to 10 mA) that can be used to control peripheral devices.
The analog voltage output is accessed via the DAC pins in the
Instrument Connection port (DAC + and COM),
Figure 1–3, page 7 .
The voltage is controlled using the PowerChrom software Method
tables, see the
PowerChrom Software Manual for more information.