USB to RS232 and RS232 to RS485 converter reviews

While USB->232->485 is cheaper, has anyone ever used the USB to RS485 adapters from this place (easysync-ltd)?

Their ad popped up on my site, and so I poked around a bit over there. The non-isolated converter is $49, while the opto-isolated one is $88.
 
DealExtreme (the really cheap Chinese place) just listed a 2 serial port PCI adapter card for $8.79 shipped -> http://www.dealextreme.com/details.dx/sku.24887

If I had the choice between this and a USB to RS232 adapter, I would go with the PCI card. Once installed, you end up with 2 real RS232 ports as opposed to the 'emulated' USB version.
 
oldcqr said:
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The spam has been removed and the user banned! In the future please refrain from posting in response to the spam. Use the report post button or contact a mod or myself via pm.
 
Summary: DealExtreme seems to have changed their chipset in the USB adapter, leading to issues when used with an unpowered RS485 converter.

Long story:
I bought four of the USB-RS232 adapters (D.E. #5859) last year for non-Christmas uses after reading Mike's reviews. After I got the drivers installed correctly, they performed better than many of my other serial adapters. So when I added some REN SS hardware and a LED-Triks (with Triks-C) this year, I ordered more of these adapters and also bought the RS232-RS485 converter (D.E. #9309) that Mike recommended. I tested all of the 232-485 converters with my old adapters and they all worked great. Problems arose, however, when I went to try out my new USB-RS232 adapters. I had trouble installing the drivers included on the CD or downloaded. After a little bit of research online, I found that DealExtreme had changed the chipset used in the converter. I downloaded the new driver and it installed fine, but would never control my triks display. I opened a few of these up and compared to the insides of one of my old PL2303 chipset converters. While I found some rough looking solder joints, those were not the cause of my problems. I noticed that the MAX211 chip is no longer included. I then suspected that the adapter must not be providing the proper voltages for the 485 adapter to operate due to this missing chip. By hooking up 5v to the breakout board on the 485 adapter, I was able to get the USB-RS232 adapter to work.

I just wanted to throw my experiences out there in case anyone else has or will run into this problem.

-Matt
 
Wow, that stinks! I'm sorry they changed things on you :(

I will definitely add your experience to my review about the RS232 adapter.
 
I am also looking into the more direct path of USB to RS485 convertor myself and this thread is really helping out.

I have had some issues with my USB to RS232 on my XPX Dell (Prob operator error). Laptop and netbook load the dirvers and operate it just fine.

I am at work right now and I can't remember the product name. Will check it out tonight and update my post.

Look forward to more feedback on the best products.

Regards,
Lightman
 
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.
 
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.
 
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
 
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.
 
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