RS485 NetWork ( x170 Inputs -> 3x Outputs ) - Page 1
Forum section: electronics / projects

author: ElectricGuy
author_rank: Regular Contributor
timestamp: February 02, 2015, 11:41:33 am
content: Hi to all;I need to implement a solution where i have 170 modules with just on input so i can connect a switch, a 3 modules with a relay output.If i press any of switches, the relay turns on. As simples as this.Please see attachment.Does someaone knows whre can i find a comercial solution for this?Thank you

author: nctnico
author_rank: Super Contributor
timestamp: February 02, 2015, 12:12:45 pm
content: Sounds like a door opener system for an appartment building.

author: ElectricGuy
author_rank: Regular Contributor
timestamp: February 02, 2015, 12:31:38 pm
content: Quote from: nctnico on February 02, 2015, 12:12:45 pmYes it is!!!!All the appartments allready has the Swtich's, and all the wiring for the RS485 interface. I just need the modules.We don't want any intercommunication system.

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 02, 2015, 12:52:12 pm
content: Why so "high tech"? Are there other requirements not revealed here? Do you need to know WHICH button was pressed? Are you logging or something?The obvious solution would be to simply wire all the buttons in parallel. Can you tell us why that was rejected? It would help us better understand the requirements.

author: ElectricGuy
author_rank: Regular Contributor
timestamp: February 02, 2015, 01:08:56 pm
content: Quote from: Richard Crowley on February 02, 2015, 12:52:12 pmHi Richard, is precisely because of that. IT will be necessary to log in the future.But at this moment only the switchs, relays and the interfaces(485).Do you know any equipment for this? ( comercial)

author: Richard Crowley
author_rank: Super Contributor
timestamp: February 02, 2015, 01:33:01 pm
content: There seem to be several small boards that use a MAX485 and an 8-pin micro (ATtiny, etc.)Here is something similar:http://www.electro-tech-online.com/threads/finished-project-rs485-network-1-master-8-slaves.115153/It was designed for only 8 nodes, but that does not appear to be a hardware limitation, only software.What is the wiring? How many conductors? Star? Daisy-chain? Cat-5 or something?How are you planning to power all those nodes?There are several other design considerations. How did you decide what wiring to install and how?

author: ElectricGuy
author_rank: Regular Contributor
timestamp: February 02, 2015, 01:38:07 pm
content: Quote from: Richard Crowley on February 02, 2015, 01:33:01 pmThanks for the link.I have cat5 between floors, so 8 conductors. I have 6 apartment p/floor, so i probably will power them locally by floor. But it depends on the specifications of the equipment that i can find.

author: gman4925
author_rank: Regular Contributor
timestamp: February 02, 2015, 01:57:59 pm
content: There are many brands of Modbus or BACnet products that will fit your requirements, it will just come down to finding the one that gives the best price per io point as most io modules will be multiple io per unit.There are other protocols that could be used too.You would also then need a controller to read and write to all the io and handle the logging in the future.You will need RS485 repeaters to split the RS485 bus so max 32 slaves sit on each section of the bus.

author: Codemonkey
author_rank: Regular Contributor
timestamp: February 02, 2015, 02:08:05 pm
content: Quote from: gman4925 on February 02, 2015, 01:57:59 pmNot required if the hardware uses 1/4 load transceivers (MAX487, LT1487 etc). I've previously designed & deployed a system that had up to 100 devices per bus spread across a large multistory buildings or big sprawling sites.

author: gman4925
author_rank: Regular Contributor
timestamp: February 02, 2015, 02:29:20 pm
content: Quote from: Codemonkey on February 02, 2015, 02:08:05 pmI didn't know about those chips, will keep them in mind for the future.I'm pretty sure that 32 slaves will be the max for most commercially available RS485 products.Some might be available that use the 1/4 load transceivers but I think they would be rather rare (and therefore possibly increase the cost) and it will probably come down to number of repeaters vs increased module cost.

author: CM800
author_rank: Frequent Contributor
timestamp: February 02, 2015, 06:42:14 pm
content: I would personally go for CAN2.0

author: ElectricGuy
author_rank: Regular Contributor
timestamp: February 02, 2015, 07:50:35 pm
content: Thank you all for your answers.gman4925, can you pont me out some devices that you are talking?By the way there are also transceivers with 1/8 unit load, so you can have 256 devices on a bus.http://www.maximintegrated.com/en/products/interface/transceivers/MAX1483.html

author: JVR
author_rank: Regular Contributor
timestamp: February 02, 2015, 07:53:23 pm
content: Id build that. Should not take more than a week to get into production

author: ElectricGuy
author_rank: Regular Contributor
timestamp: February 02, 2015, 07:56:54 pm
content: Quote from: JVR on February 02, 2015, 07:53:23 pmYou are right, it is very simple, but i don't have the time to do it, i prefer bying something allready on the market.

author: gman4925
author_rank: Regular Contributor
timestamp: February 02, 2015, 08:03:41 pm
content: Look at Novus DigiRail 4C, DigiRail 2R for an example of low IO modules, you will usually find that most are 8 or 16 IO.Look at some cheap PLC that talks modbus like Delta or Koyo Click.There will be many options, I would say talk to an automation company that is local to you.

author: gman4925
author_rank: Regular Contributor
timestamp: February 02, 2015, 08:12:02 pm
content: http://www.bhb.pt/They are distributors for Novus in Portugal

author: ElectricGuy
author_rank: Regular Contributor
timestamp: February 02, 2015, 08:14:48 pm
content: Quote from: gman4925 on February 02, 2015, 08:12:02 pmMany thanks!!!

author: SL4P
author_rank: Super Contributor
timestamp: February 02, 2015, 11:54:05 pm
content: I may have missed this, but with 170 people able to open the door, how does person #xxx know there is someone at the door waiting to be opened ?(Yell out, look over the balcony, walk back inside and press the button ?)

author: ElectricGuy
author_rank: Regular Contributor
timestamp: February 02, 2015, 11:55:24 pm
content: Quote from: SL4P on February 02, 2015, 11:54:05 pmThat situation is allready considered.

author: emcarro
author_rank: Newbie
timestamp: February 05, 2015, 09:06:45 am
content: Hello.I´ve sent a private mesage showing more or less the products in our company that may help you. They are quite simple and have been tested for long time. They are reliable and you can configure them as you want.Hope its interestin for you.