USB to RS232 and RS232 to RS485 converter reviews

[budude]

It looks to be USB to RS232

Yep - it is - http://www.trendnet.com/products/pro...0_TU-S9&cat=49

[lightman]

Thanks for the clarification.

[kfindley]

http://www.onbene.com/Products/979-xhd-1010.aspx
I use this one this year and it works great i got it in about days after ordering

[ben&bobbi]

Yep - it is - http://www.trendnet.com/products/pro...0_TU-S9&cat=49

does this one come with software for WIN7 - easy to setup?

even though this is RS-232, can't you just use the $.65 adapter from monoprice, converting from RS-232 to CAT5 and run CAT5 cable as long as you want to? Reason i am asking, i think my OLD laptop won't make it, so i might have to use my newer one, with no serial port and WIN7.

[rokkett]

No, converting the cabling/connector type is not the same as changing from RS-232 to RS-485.

The RS-232/RS-485 standards not only specifies cabling and connector types, but defines, primarily, the electrical communications standards. Electrically, RS-232 uses a shared common ground and is very susceptible to noise. This is the reason for the shorter cabling distances. The RS-232 spec calls for cables lengths less 50 feet for the speeds we are using with the Renard devices.

The RS-485 standard does not use a shared ground, but rather a two-wire voltage differential communication protocol. Because of this, it is not as easily affected by electrical noise on the wire, hence the much longer allowed cabling distances - up to 4000 feet.

Long story short, simply changing the connectors on the end of the wire will not change the electrical communication protocol.

[rokkett]

Just clarify - you can send RS-232 down cat5 cable and use RJ45 jacks, I was just pointing out that doing that will not convert the signal from RS-232 to RS-485. It would still be limited in the length of cable to the much shorter RS-232 spec.

Here is an post I did last year showing how to build a DB9 to RJ45 cable. Still RS-232, but as long as you set the jumpers correctly, this plugged into a SS24 about 40 feet away, just fine.

Coming out of the first board to the second, third, etc boards will all be RS-485 because of the circuit design and chips used to generate the serial communication.

[jhartley]

rokkett,

I read your earlier post about the DB9 - RJ45 cable, and it brought up the question for me, why would I then need a RS-232/RS485 converter if I can go straight from DB9 to RJ485, which you answered in the previous post. Thank you for that. I do have another noob question. I recently watched the following video ( http://www.youtube.com/watch?v=GNW6qKscRyY ) where 2 data wires were connected to the RS-232/RS485 adapter, 3 were connected to power, and 3 connected to ground. I plan to run from this RS-232/RS485 adapter to a SS24 board, do I need to pass power/ground down the cat5 with the SS24 as my first board?

Jon

[rstehle]

That post was for the Ren 16 Xmus version, which does not have an onboard Power Supply. It gets power from and external 12v source, like a PC power supply. You only need to use Pins 4 & 5 and a ground for most other Renard boards.

[jhartley]

Perfect! Thanks again. I found the wiring diagram. I should be all set.

[FisseHans]

Nice review, makes it easier to make a decision! Here is also some general information about what a RS232 to RS485 converter is and how it can be connected. More like a wiki page.