SMA WEB-BOX RS 485 link connections?

IronLiver · Nov 9, 2011

I have a Webbox to link up to an externally located STP 10000TL via RS 485, has anyone carried out this type of coms link yet? On recommendation of a supplier I sourced 100m of RS 485 shielded cable containing a twisted pair. The STP installation maual shows one core being used for + and one for - then the foil clamped into the RS485 interface. Having received the webbox today I unboxed it and found the other end (at the webbox) showing an additional core used as the ground in one of the screw terminals. There is no provision for clamping the sheath at the webbox end.

Can i just use the sheath for this ground link as per the other end or do I need to get another drum of cable with 2 twisted pairs so that I can use one core as a dedicated ground link? Will try to get in contact with SMA if I can tomorrow but any help you can offer would be gratefully received.

Cheers

morpheus75 · Nov 10, 2011

i had this hooked up and i just used cat5 network cable. ok it was only a 50cm length but it worked. i used 1 twisted pair as my + and - and then just a single core for ground connection.
it worked perfectly.

IronLiver · Nov 10, 2011

The array is about 60m from the webbox that's why I thought rs485 was the best option

morpheus75 · Nov 10, 2011

the ground connection doesnt need to be a twisted pair, just a single core will work.

IronLiver · Nov 17, 2011

Thanks for the responses, the inverter is going in next week and I decided to send the cable back and get a drum with two pairs instead, will just cut one of the cores back. Wish I'd just used the Cat5 now as I have a load of that already!