hello,
working on a permanent exhibition and including arduino UNO boards inside, I'd need to know what would be the best (permanent) connectors or what would be the best way to connect permanently long wires to the board.
I thought about crimp connectors or other ones but I'd probably have to glue them no?
About wires, we'd use long wires and I guess shielded wires would be the best way.
any ideas/experiencies/links would be appreciate.
all the best,
There are shields available that bring out pins to terminal blocks and various connectors - have a look around.
If you are using long wires (> 2--5m?) you might need to go to twisted pairs (don't use shielded/coax, the characteristic impedance is too low for logic signals). For very long runs (> 5--10m?) you will need to terminate logic signals with termination resistors (outputs from the Arduino can drive 220 ohms which is a good match for twisted pairs - other devices may not be so powerful).
Analog runs can be shielded though as the bandwidth is vastly lower.
Low bandwidth buses (TWI, One Wire) are more tolerant but pull up resistors need to be present at both ends of the bus if long - there are quite a few web resources out there in this case.
For extremely long runs you need differential line drivers and receivers - or consider wireless links.
If your setup has a choice of pulse width, use longer pulses for longer cable runs...
Don't expect full-speed SPI bus to work reliably over a long cable, it just isn't designed for that - lower speeds may well work but do test everything with the full length cable before committing the design!
Twisted-pairs:
For each logic signal run a ground wire with it as a twisted pair. CAT5 cable is useful as its 4 twisted pairs with guaranteed high performance - so RJ45 connectors can be a good choice - do checkout the pinouts of standard ethernet cable for where the pairs connect at each end (though you can usually make out the colour codes in the plug)
hello and thanks A LOT for your interesting post.
I'll only need too read voltage from IR distance sensor which will be supplied by a special adapter (I need 20 sensors which would be around 2A for the whole)
But those wires could be around 10m (maxi)
This will be only analog signals so... I don't know if I'd need pull up/down resistor or termination ones.
Maybe you could tell me.
About connectors on the arduino side, I thought about glueing them.
I'll probably use a box like that: http://www.smartprj.com/catalog/index.php?main_page=product_info&products_id=9
any ideas about connectors solid & robust ?
Permanent: unsolder the connectors and solder the shields directly into place. Solder is electrical glue 
Another possibility (for individual wires) would be to solder individual wire-wrap (square) header pins, then wire-wrap the connectors (wire wrapping is a -much- stronger mechanical bond than soldering, especially where vibration is an issue). Of course, then the weak point would the solder joint (in order to eliminate all this, you'd have to build a standalone Arduino using wire-wrap sockets, etc).
thank a lot for all your informations & experiencies!
I'll probably use a box and that one will be glued on a flat surface and won't move.
about making my own boards, it is a bit too late in the process.
about pull down resistor & termination resistor.
as I'll only use analog connection, do I need them? or are shielded wires enough ?
KE7GKP,
here is the datasheet of my sensor.
About wires, I don't know, it one of my questions 
About distance, it could be around 5m maximum.
sharp_IR_300cm.pdf (272 KB)
hello and thanks a lot
finally, I have the choice to buy analog or digital distance sensor.
I don't know what would be the most safe...
- What exactly are you measuring?
I only want to detect a person who cut the ray.
if (distance< D) then trigger something.
- How fast is it moving?
It can be fast indeed
but only a walking person, not running.
- How often do you need to update the distance measurement?
saying.. every 200ms (considering 2) )
- What exactly are the analog and digital sensors you are selecting from
I linked the sharp one in the previous post.