Aim-TTI LD400, Инструкция по эксплуатации

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13
Terminal Blocks
All other rear panel connections are made via the screw-less terminal blocks. To make
connections to the terminal blocks, use a flat screwdriver to press the spring-loaded orange
actuator inwards to open the wire clamp; insert the wire end fully into the hole and release the
actuator. Ensure the wire is properly gripped. Take care to observe the marked polarity.
Current Monitor Output
The top pair of terminals, marked CURRENT MONITOR, provide the current monitor output.
They are wired in parallel with the front panel Current Monitor sockets and the same
requirements apply, see above.
Remote Control Voltage Input
The CONTROL VOLTAGE terminals are used in two operating modes of the instrument:
In EXTERNAL VOLTAGE mode an analogue signal applied here sets the level of the load; the
scaling is 4 Volts full scale.
In EXTERNAL TTL mode, a logic signal applied here selects either the LEVEL A setting (logic
low) or the LEVEL B setting (logic high). The switching threshold is nom1·5V.
These terminals will tolerate a common mode voltage of up to ±100 Volts relative to
the negative terminal of the load input. The input impedance is 400k
Ω
from each
terminal to the load negative, so a common mode current will flow.
External Voltage Sense Input
To avoid errors in sensing the voltage of the source caused by voltage drops in the high current
wiring, connect the EXTERNAL SENSE terminals to the external circuit at the point where the
voltage needs to be measured (normally at the output terminals of the source under test). Move
the VOLTAGE SENSE SELECT slide switch on the rear panel to the EXT position.
Ensure that the source is connected with the correct polarity.
These terminals must not be connected to any voltage other than the source that is
connected to the load input.
Remote Disable Input
Apply greater than +3V (pref5V) to the DISABLE INPUT terminals to disable the load
input; these are the input to an opto-coupler, through 1k
Ω
, and are galvanically isolated from all
other terminals. The input current is less than 2·5mA at 5V.
The maximum input voltage is +12Vdc. Avoid reverse polarity.
Oscillator Sync Output
The SYNC OUTPUT is an open collector output of an opto-coupler driven by the signal from the
internal oscillator; it is galvanically isolated from all other terminals. A suitable pull-up resistor and
power supply (e.g. 4·7k
Ω
to +5V) are needed to generate a usable signal, which could be used
to trigger an oscilloscope. There is a 1k
Ω
series protection resistor.
The maximum collector supply voltage is +30Vdc. Avoid reverse polarity.
The load resistor should be chosen to source ideally 1mA, maximum 2mA.
Digital Remote Control Connections
The LD400P model provides full remote control capabilities through standard LAN, USB, GPIB
and RS232 interfaces. All of these are isolated from the load input terminals of the unit. The USB,
GPIB and RS232 interfaces are connected to chassis ground, and care must be taken to avoid
introducing ground loops. The LAN interface is isolated by standard network transformers.
Full details are given in the ‘Remote Interface Configuration’ chapter later in this manual.