Good USB RS485 interface? - Page 1
Forum section: electronics / general

author: nctnico
author_rank: Super Contributor
timestamp: August 06, 2014, 11:36:01 am
content: I'm a bit stuck between a rock and a hard place. I have a serial device which I need to operate using an RS485 interface instead of a regular full duplex serial port. The problem is that the device starts to send data back right after it has received the last byte so the RS485 bus has to switch from transmit to receive really quick. The RS485 adapter I'm using uses the RTS line to control the RS485 transmit but that lags behind a few ms. Does anyone know an RS485 interface which has some intelligence onboard to switch the RS485 quicker?

author: David_AVD
author_rank: Super Contributor
timestamp: August 06, 2014, 01:05:32 pm
content: If you use the FT232RL it has a Tx enable line to run out to your MAX485 chip. Not sure what the turnaround time is exactly though. Has to be better than using RTS.

author: IO390
author_rank: Regular Contributor
timestamp: August 06, 2014, 01:56:45 pm
content: http://www.kksystems.com/KKSystems have some good stuff if that helps.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 06, 2014, 02:19:54 pm
content: Yes - FTDI chips do it properly - shouldn't be an issue with turnround time - I use them at megabit rates.FTDI make a number of USB-485 boards,. and Easysync (part of FTDI) do several cased products based on the FTDI boards.

author: nctnico
author_rank: Super Contributor
timestamp: August 06, 2014, 03:12:10 pm
content: I have several FT232 boards lying around. I just never thought FTDI would be so clever to make their devices suitable for RS485 out of the box.Thanks!Edit: I modified one of my FT232 boards and it works like a charm (with an external RS485 transceiver). I just ordered some FT232 based RS485 converter boards through Ebay to have some in stock.

author: Monkeh
author_rank: Super Contributor
timestamp: August 06, 2014, 03:38:13 pm
content: Quote from: mikeselectricstuff on August 06, 2014, 02:19:54 pmI would not order anything from EasySYNC. Their website has been rather visibly compromised for many months now.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: August 06, 2014, 03:41:29 pm
content: Quote from: Monkeh on August 06, 2014, 03:38:13 pmIn what way?

author: Monkeh
author_rank: Super Contributor
timestamp: August 06, 2014, 03:42:23 pm
content: Quote from: mikeselectricstuff on August 06, 2014, 03:41:29 pmScroll down to the bottom of their front page.E: Okay, now I'm beginning to wonder. I know my machines and router are secure, and yet I don't see that over 3G or a proxy. I think I shall investigate further.E2: Clean machine, at my modem. Still there. Cannot see via 3G (Three), tunneled to Germany or America, friends on BT connections.. See attachment. Time to phone my ISP.E3: These should load and look suspicious for everyone:http://easysync-ltd.com/amnuthspely/so-now-you-know-a-bit-about-us-ckoqbkwelqmj.htmlhttp://easysync-ltd.com/amnuthpapserm/share-on-email-print-odontogenic-lesions-overvie-strepe-riplock.htmlI will stand by my suggestion to be wary at this time.

author: Quiggers
author_rank: Contributor
timestamp: September 15, 2016, 11:14:01 am
content: Web site looks clean from here, none of that rubbish at the bottom like in the image you posted.Can anyone tell me ifhttp://www.easysync-ltd.com/product/590/usb2-h-9004-m.htmlappears as multiple com ports or as one com port?Anyone have any experience of these?http://www.advantech.com/products/5754ec6c-de46-4543-ab4e-f2a8d3e96c9c/pcie-1602/mod_00018e92-1b31-42e8-a930-9b3a2af8de2c

author: Monkeh
author_rank: Super Contributor
timestamp: September 15, 2016, 02:46:03 pm
content: Quote from: Quiggers on September 15, 2016, 11:14:01 amIndeed, I've only ever seen that through my previous ISP. And yet, the link I posted still works from anywhere.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 15, 2016, 03:14:22 pm
content: Quote from: Quiggers on September 15, 2016, 11:14:01 amMultiple port boxes appear as the corresponding number of ports. 16 port boxes can take a while to install drivers....

author: Quiggers
author_rank: Contributor
timestamp: September 20, 2016, 02:01:25 pm
content: Thank you Mike.

author: bicc1306
author_rank: Contributor
timestamp: September 21, 2016, 02:44:34 pm
content: Quote from: Quiggers on September 15, 2016, 11:14:01 amI don't had any experience with them. I am a beginner in circuit board industry and most of times I have listen is all about pcbway and pcbshoppers.

author: Delta
author_rank: Super Contributor
timestamp: September 21, 2016, 02:49:50 pm
content: Do you only have the one device on the bus? I was looking for a PC - RS485 interface for a multidrop bus, but even after speaking to various manufacturers, I could not find one that supported 9bit mode...

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: September 21, 2016, 03:06:48 pm
content: Check the FTDI programming guides to see how/if their chips support 9 bit modes

author: ebclr
author_rank: Super Contributor
timestamp: September 21, 2016, 03:08:08 pm
content: Take a look on this producthttp://www.icpdas.com/schp/schp/detail.php?module_no=I-7520A