My Name is Matt Weighman and I am currently a final year marine engineering student studying at the University of Greenwich in the United Kingdom. As part of my third year studies I am required to undertake project based work. Mine involves designing part of a marine engine room simulator. The university eventually hopes to build this simulator and interface the real hardware with a software programme. The interfacing is hoped to be achieved using your companies product, specifically the Velleman K8061 Extended USB interface board and therefore I am researching how this might be achieved and would most appreciate any help your company could give. Interfacing is a subject with which i am unfamiliar so forgive me for my lack of knowledge. We hope to simulate a number of functions with the system such as having panel meters/gauges displaying various parameters, LED ladders displaying tank levels, switches or potentiometers to simulate the opening and closing of valves and buttons to start and stop various items of equipment. I therefore have a number of questions which i would be very grateful if you could help me with:
What is the limit to the current that can be drawn through the board and through each input/output?
Is it possible/better to use the outputs to activate relays and have the hardware or instruments powered from an external source?
Can the digital inputs be connected directly via a switch or pushbutton to the board from a correctly rated external power supply? And can the analogue inputs be directly connected via a potentiometer?
The project is in its early stages and you must forgive me for my inexperience in the subject
[quote]1) What is the limit to the current that can be drawn through the board and through each input/output?[/quote] You’ll find answer to this question on pages 2 and 9 of the manual.
[quote]2) Is it possible/better to use the outputs to activate relays and have the hardware or instruments powered from an external source? [/quote] Indeed, it is better to use relays and external power source. The connection of the relay between the CLAMP and the digital output is shown on page 13 of the manual.
[quote]3) Can the digital inputs be connected directly via a switch or pushbutton to the board from a correctly rated external power supply? And can the analogue inputs be directly connected via a potentiometer?[/quote]Yes, you can. You can connect switches simply between the digital inputs and GND. There are pull-up resistors on the board.
To the analogue input you have to feed 0…5V or 0…10V from an external voltage source via a potentiometer.
Thankyou for your advice, it will be most helpful.
One other issue that has come up is what is the best way to connect instruments from the anologue outputs when the full voltage range is required since a relay cannot be used?
Could you please describe more detailed what kind of instruments you are going to connect to the K8061.
The best way of connection depends on the specifications of the instruments (e.g. resistance, voltage, current…).
The instruments we wish to connect to the anolgue ouputs are panel meters of the moving coil type. The specifications are as follows:
Types: D48MC, D72MC, D96MC
Accuracy: Class 1.5
DC Ratings: 100µA to 50A direct connected (D48MC-40A max)
4-20mA, 1mA or 20mA transducer operated.
50mV to 600V direct connected.
50mV to 300mV shunt operated.
DC Burden: 80mV to 150mV volt drop for direct connect
ammeters, 1mA (1000W/V) for voltmeters and
shunt operated ammeters.
We were wondering if it was possible to connect these directly to the board or whether some other means would be necessary.
This kind of voltmeter, 1000 ohm/V, you can connect directly to the output of the K8061.
Please note that there will be about 1V voltage drop at the K8061 output due to the load current of the meter. If you select 10VDC meter you never get full reading.