Problem Reading Serial Port (RS485)

Started by andrea1984 in comp.arch.embedded8 years ago 3 replies

Hi all, I've a FOX Board (Linux Embedded) with RS485 port, and a Power Counter (RS485 too) that work at 9600E1. With a USB to RS485 cable and...

Hi all, I've a FOX Board (Linux Embedded) with RS485 port, and a Power Counter (RS485 too) that work at 9600E1. With a USB to RS485 cable and windows i can successfully communicate with the Counter, writing a simple c# application. The rs485 linux board work too (with others devices). I can't read always correctly between the linux board and the counter, and i don't know why. I've analyzed wi...


2 wire rs485

Started by Vasilis in comp.arch.embedded8 years ago 70 replies

Hello list, I'm having problems talking to a 2 wire rs485 device. This is my following configuration: - embedded pc104 board AAEON...

Hello list, I'm having problems talking to a 2 wire rs485 device. This is my following configuration: - embedded pc104 board AAEON PFM-530I - programmable electricity meter with rs485 interface for communication. Now, setting a few jumpers on the board toggles an rs485 port on ttyS1. My specific problem is this: i don't seem to connect the board and the meter correctly. This is what...


RS232 or USB to RS485

Started by QBA in comp.arch.embedded13 years ago 34 replies

I need RS232 to RS485 converter or USB to RS485 converter, are there vendors out there you recommend for these converters? More specifically,...

I need RS232 to RS485 converter or USB to RS485 converter, are there vendors out there you recommend for these converters? More specifically, RS485 I am using is 2-wire (ground, don't need 4-wire version) at 19200 baudrate.


Monitoring RS485

Started by Daniele in comp.arch.embedded12 years ago 23 replies

Hi all, i need an informatio about rs485: I need to watch netwrok trafic from my device and another device that use rs485 to comunicate....

Hi all, i need an informatio about rs485: I need to watch netwrok trafic from my device and another device that use rs485 to comunicate. Is possible to connect in parallel mode another peripherical (like a pc via rs232) to trace all the message that is exchange from two device? Thanks in advanced Daniele


WTD Addressable RS485 to RS232 Serial converters

Started by Joseph Goldburg in comp.arch.embedded13 years ago 1 reply

Hi All, I am looking for RS232 to RS485 serial converters. Requirements ---------------------- The converter should have a small buffer 20...

Hi All, I am looking for RS232 to RS485 serial converters. Requirements ---------------------- The converter should have a small buffer 20 bytes to 1k bytes. The converter should have an RS485 address. Thus the converter listens to the RS485 bus traffic.... if it spots it's address then a. It listens for a quite time on the RS485 bus then transmits header address and then the data...


RS485, multidrop protocol

Started by Ian McCrum MI5AFL in comp.arch.embedded13 years ago 32 replies

I wonder if there is documentation on standard RS485 protocols anywhere for download? I have homebrewed a couple of these in the past but is...

I wonder if there is documentation on standard RS485 protocols anywhere for download? I have homebrewed a couple of these in the past but is there a standard way of doing this? I am interested in using the serial port of a linux machine, with RS485 line drivers/receivers and probably RTS control to effectively network a number of machines together. Two possible applications spring to...


RS485 chip LTC491; optocoupler MOC5007

Started by Shane williams in comp.arch.embedded6 years ago 14 replies

Hi I'm a software engineer wondering about some hardware. We have a circuit board with RS485 circuitry and Motorola 68302 processor using an...

Hi I'm a software engineer wondering about some hardware. We have a circuit board with RS485 circuitry and Motorola 68302 processor using an LTC491 RS485 chip and MOC5007 optocoupler for electrical isolation. The RS485 circuit is arranged to run as either 4 wire multidrop (with contention detection circuitry) or as two by 2 channel half duplex point to point, with each channel 2 wires. ...


[RS485] can't perform handshake.

Started by SarAVR in comp.arch.embedded10 years ago 4 replies

Hello all. I am just a novice who wants to use ATmega8535 as a means to control RS485 communication devices. Communication type to implement...

Hello all. I am just a novice who wants to use ATmega8535 as a means to control RS485 communication devices. Communication type to implement is full duplex and I used two MAX485 transceiver ICs per one board, one for transmitting and the other for receiving. As I burned ATmega microcontroller of main board with my code by ISP programmer, RS485 communication seemed work well without any er...


RS485

Started by jjvijay in comp.arch.embedded11 years ago 1 reply

As we know In RS485 we can connect 32 nodes.,I have one doubt in RS485 Standard we can use upto 4000ft (distance)...will this length is between...

As we know In RS485 we can connect 32 nodes.,I have one doubt in RS485 Standard we can use upto 4000ft (distance)...will this length is between 2 nodes or we have to connect 32 nodes within this lenght(distance)...I am waiting for the valuable solution.... urs vijay


RS232 software virtual hub

Started by pozz in comp.arch.embedded2 years ago 4 replies

I often work on small electronic devices that communicates over a multi-drop half-duplex two-wires RS485 network. I usually try to compile...

I often work on small electronic devices that communicates over a multi-drop half-duplex two-wires RS485 network. I usually try to compile all the projects for the developing Windows machine (I use mingw as the compiler). Simulating and mimic the hardware in some way. The best simulation for the RS485 is a typical RS232 port with a RS232-RS485 attached (actually it is a very cheap USB-...


RS485 is bidirectional does it mean it is fullduplex?

Started by Swizi in comp.arch.embedded12 years ago 160 replies

I was told by my professor that specification of RS485 is a half duplex RS485 four wire mode has got four pin Rx+, Rx-, Tx+, Tx-. Where the...

I was told by my professor that specification of RS485 is a half duplex RS485 four wire mode has got four pin Rx+, Rx-, Tx+, Tx-. Where the maste device Tx+ and Tx- will be connected to the slaves Rx+ and Rx respectively. Simlarly Master's Rx+ & Rx- will be connected to the slave' Tx+, Tx- . Other than the master all the device will be in receive mode, s if only there is the transmission RTS ...


RS-485 Troubleshooting

Started by RahulS in comp.arch.embedded11 years ago 16 replies

Hi, I am using Rabbit development board which has separate ports for RS232 and Rs485. Right now i am using a single port both as RS232 as well...

Hi, I am using Rabbit development board which has separate ports for RS232 and Rs485. Right now i am using a single port both as RS232 as well as RS485. The port works fine for RS232 signals but for RS485 signals, the differential output is not proper.I think there is some problem with the differential voltages. Please help.


8051 and RS485 how to

Started by raje...@gmail.com in comp.arch.embedded10 years ago 7 replies

I want to communicate with 10-15 micro controllers from the host micro controller. Each node(independent micro controller) may be around...

I want to communicate with 10-15 micro controllers from the host micro controller. Each node(independent micro controller) may be around 500 meters distant from the host. The no. of micro controllers and the distance may increase. I feel I should use RS485. Anybody, please let me know what should be done for RS485 ? I am OK with RS232. Please help, Thanks !! rajeshbij@gmail.com


RS485 A/B line reversal in extant devices

Started by Steve at fivetrees in comp.arch.embedded13 years ago 2 replies

Every time I design a product with an RS485 interface, I wind up going over the same old ground in disbelief - and coming up with the same...

Every time I design a product with an RS485 interface, I wind up going over the same old ground in disbelief - and coming up with the same answer. The A/B line-naming convention is reversed when comparing extant devices (e.g. the venerable SN75176B, or the transceiver product line from Maxim) with the RS485 (ok, EIA485) specification. Perhaps this confusion stems from the definitions and in...


Any experiences running 460 kbaud RS485?

Started by Mike Silva in comp.arch.embedded8 years ago 3 replies

We're looking at a design that would have 1 RS485 master and 2 slaves, with a maximum cable length of 50 meters (25m is more likely), and we'd...

We're looking at a design that would have 1 RS485 master and 2 slaves, with a maximum cable length of 50 meters (25m is more likely), and we'd need to run a data rate of 460 kbaud. Since the RS485 spec talks about data rates of 10 Mbaud and cable lengths of 1200 meters (not at the same time) it would seem that we're well within safe-and-sane territory, but I was hoping to hear from anybody w...


RS485 guard-time

Started by pozz in comp.arch.embedded1 year ago 6 replies

I just noticed a nice feature of SAM C2x microcontrollers from Atmel. It is the RS485 support, i.e. one pin (TE) goes high when the UART is...

I just noticed a nice feature of SAM C2x microcontrollers from Atmel. It is the RS485 support, i.e. one pin (TE) goes high when the UART is transmitting and goes immediately low when the last byte was really shifted out, including stop bits. There is an additional feature that Atmel named "guard time". " For RS485 mode, the guard time is programmable from 0-7 bit times and defines t...


Does RS422/RS485 work on Advantech PCM-5820?

Started by Lewin A.R.W. Edwards in comp.arch.embedded13 years ago 2 replies

I just received an unpleasant surprise when trying to use differential serial on the Advantech PCM-5820. The system has jumpers for the second...

I just received an unpleasant surprise when trying to use differential serial on the Advantech PCM-5820. The system has jumpers for the second serial port; RS232, RS422 or RS485. In either RS422 or RS485 mode, I see no activity at all on the TxD+/- pins. My software is asserting DTR and RTS, so I don't know what else I could possibly do to enable the drivers (and they should always be enab...


Is termination needed for short and slow RS485?

Started by mrsoft99 in comp.arch.embedded13 years ago 11 replies

We are running some led billboard displays using a multi-drop 2-wire RS485 network. The cable length is 50 feet; the baud rate is 2400...

We are running some led billboard displays using a multi-drop 2-wire RS485 network. The cable length is 50 feet; the baud rate is 2400 baud. Are RS485 terminators really needed for this? I know they are needed for 'long' cables and 'fast' baud rates, but does 50 feet at 2400 baud qualify for this? And yes the reason I am asking is there are some problems with some of the displays. (If...


RS 485 on advantech PCM-4153 board

Started by muktabh in comp.arch.embedded9 years ago 1 reply

Hi, I have an advantech PCM-4153 board with 4 com ports. The user guide says port 2 can be configured as a RS485 port. I have a few doubts. I am...

Hi, I have an advantech PCM-4153 board with 4 com ports. The user guide says port 2 can be configured as a RS485 port. I have a few doubts. I am using linux on this board. Will I need special drivers to use RS485? (the board uses sch3112 chip for IO) The user guide says to set a jumper to switch from rs232 to rs485. Will I need to change the serial comm code too? Is it OK if i do this: 1) COM ...


RS485 Networking

Started by suparoo in comp.arch.embedded9 years ago 2 replies

Hi, would anyone be able to point me in the right direction for RS485 network training? Cant find anything online and need to rectify...

Hi, would anyone be able to point me in the right direction for RS485 network training? Cant find anything online and need to rectify an intermittent fault on a relativly basic 485 over mm fibre setup. Any info on testing would be most welcomed, but please understand my existing knowledge is limited to say the least! Many thanks for any input Suparoo