Embedded Ethernet

Started by pozz in comp.arch.embedded2 years ago 38 replies

There are many MCUs with embedded Ethernet (MAC). It seems most of the open-source examples are lwip-based. I have to design a board with one...

There are many MCUs with embedded Ethernet (MAC). It seems most of the open-source examples are lwip-based. I have to design a board with one RS485 port and one Ethernet port. It could be seen as a serial-to-Ethernet converter, where the protocol on RS485 is proprietary. On Ethernet side I will contact a server (cloud) with a protocol that must be defined. At the moment, I don't need...


PPP over RS485 - Speed

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

Hi, I am working on increasing the speed of data transfer between two electronic modules(each running OSE operating system)using...

Hi, I am working on increasing the speed of data transfer between two electronic modules(each running OSE operating system)using PPP(supported by OSE)over RS485. However be the baudrate i configure the maximum speed i get is 8KiloBits per second. Even if the baud rate has been changed to 38400kbps or higher it does increase the transfer rate. Is there some reason why it doesnt?It will be grea...


Two quick RS-485 questions

Started by Lewin A.R.W. Edwards in comp.arch.embedded15 years ago 32 replies

Hi all, I have to implement a very simple multidrop RS485 application, carrying slow 2400bps or even 1200bps data from a PC to a...

Hi all, I have to implement a very simple multidrop RS485 application, carrying slow 2400bps or even 1200bps data from a PC to a half-dozen devices about 300 feet away. The data flow is unidirectional; the devices don't talk back. Low cost is a significant factor in this. I plan to stick an RS485 driver on an AVR, weld on the small additional logic I need, and put it in a box. Two quick...


Lantronix UDS1100 in multidrop RS485 application

Started by Anonymous in comp.arch.embedded13 years ago 4 replies

Hi, I've got an application that requires a number of environmental controllers be connected on an RS485 2 wire half duplex multidrop bus. I...

Hi, I've got an application that requires a number of environmental controllers be connected on an RS485 2 wire half duplex multidrop bus. I was looking at the Lantronix UDS1100 device servers (or even the older UDS100 / UDS10 ) to let me use the customers LAN so as to save wiring costs. I know a couple of UDS1100's can be placed back to back and tunnelling used to create a transparent R...


Two-wires RS485 single master multi slaves: how to define the receiving buffer

Started by pozz in comp.arch.embedded6 years ago 15 replies

I have a typical two-wires RS485 network with multiple nodes. Only one node (the master) can start a communication: it sends a packet/request...

I have a typical two-wires RS485 network with multiple nodes. Only one node (the master) can start a communication: it sends a packet/request and receives a packet/answer. Usually the slaves can't communicate without the help of the master. The slaves could be different, so running a different firmware on different CPUs. Of course, all the slaves understand a common protocol (synta...


mscomm in vc++ - parity error

Started by Jim in comp.arch.embedded13 years ago 6 replies

Hi, I'm writing some logging software for an embedded alarm panel design that uses an RS485 bus and proprietary protocol. I've attached the...

Hi, I'm writing some logging software for an embedded alarm panel design that uses an RS485 bus and proprietary protocol. I've attached the obligatory RS485 -> RS232 converter and connected to a free serial port on my PC. All good so far! Now, the alarm panel deliberately causes a parity error on the header byte of all packets transmitted on the bus. This parity error is used by all


RS485 bus with "non-true" fail-safe transceivers

Started by pozz in comp.arch.embedded6 years ago 7 replies

I have manu SN75176 (www.ti.com/lit/ds/symlink/sn75176a.pdf) that I'd like to use to create a 2-wires RS485 bus with 10 nodes. However this...

I have manu SN75176 (www.ti.com/lit/ds/symlink/sn75176a.pdf) that I'd like to use to create a 2-wires RS485 bus with 10 nodes. However this transceiver isn't true fail-safe, so the receiver, if enabled, has an undefined output (with wrong data received from the UART) if the inputs are open or shorted. This is a 2-wires bus, so only one node transmits at one time. After transmitting ...


Serial to Ethernet Device Servers on Linux

Started by Anonymous in comp.arch.embedded13 years ago 6 replies

Hello there! I am new to low level programing. I have a Moxa 5232 Device server. I have a rs485 device that I like to be able to access from a...

Hello there! I am new to low level programing. I have a Moxa 5232 Device server. I have a rs485 device that I like to be able to access from a Linux computer. It is a 2 wire 1/2 duplex rs485 enabled device. After installing the Moxa drivers I have a "/dev/ttyr00 & /devttyr01" devices/ports on my Linux server. In order for me to access this device, I wrote a C program. It basically ope...


UARTS that generate an interrupt if bit 9 = 1 ? (for RS485 protocol)

Started by Chris Graham in comp.arch.embedded15 years ago 7 replies

I am designing an RS485 network, and was reading a Circuit Cellar article by Ambekar that describes a protocol that uses 9 bit characters, where...

I am designing an RS485 network, and was reading a Circuit Cellar article by Ambekar that describes a protocol that uses 9 bit characters, where a non-zero 9th bit indicates that the character is a control character. The described network used Intel MCS51 UART that can apparently be set to generate an interrupt only bit 9 is non-zero. This way devices on the network are not interrupted...


RS485 chips and differential voltage

Started by Dennis Clark in comp.arch.embedded15 years ago 15 replies

I've been reading up on RS485 drivers like the LTC485, 75176B and others. They look too simple in pin count to supply the + and - voltages...

I've been reading up on RS485 drivers like the LTC485, 75176B and others. They look too simple in pin count to supply the + and - voltages needed for differential drives. Are there some chips that supply the +/- voltages that other chips simple scavange and use? Or do these chips I note actually supply the +/- voltages for the differential outputs? The chip specs don't say. I've a proje...


Master/slaves network protocol

Started by pozz in comp.arch.embedded5 years ago 9 replies

I have a "smart device" SD that is the master on a RS485 master/slaves half-duplex network. The user interact with a "dumb device" DD (slave)...

I have a "smart device" SD that is the master on a RS485 master/slaves half-duplex network. The user interact with a "dumb device" DD (slave) and he should have the illusion to interact directly with the SD. All the relevant (for the user) info (status and settings) about the SD must be spread among the DDs, through a suitable protocol on the RS485 network. Some variables are read-onl...


Two-wires RS485 and the driver enable problem

Started by pozzugno in comp.arch.embedded5 years ago 65 replies

I have a multi-drop two-wires RS485 bus. One node is the master and all the others are slaves. The master is the only node that is authorized...

I have a multi-drop two-wires RS485 bus. One node is the master and all the others are slaves. The master is the only node that is authorized to initiate a transmission, addressing one slave. The addressed slave usually answers to the master. The bus is half-duplex, so every node disables the driver. Only THE node that transmits data on the bus enables the driver and disables it a...


Autodetect slave devices on a bus network (RS485)

Started by Anonymous in comp.arch.embedded6 years ago 13 replies

I have a bus network (RS485 based) with one master and N slaves. Each slave has a different unique 32-bits serial number. I was thinking on a...

I have a bus network (RS485 based) with one master and N slaves. Each slave has a different unique 32-bits serial number. I was thinking on a method for the master to autodetect the serial numbers of the connected slaves. Of course, the brute force method isn't acceptable for the time to test ALL the serial numbers. A more intelligent approach could be to discover the serial number


RS485: when should I consider it a "transmission line"

Started by pozz in comp.arch.embedded6 years ago 6 replies

I know multi-drop two-wires RS485 bus must be considered a "transmission line" (so terminations are important) when the baud rate is high and...

I know multi-drop two-wires RS485 bus must be considered a "transmission line" (so terminations are important) when the baud rate is high and the cables are long, but I'm not able to quantify the "high baud rate" and the "long cable". For example, if the baud rate is 9600bps, how long could be the cables? And what if the baud rate is 38400? With those two baudrate and cables up to 10...


Half-duplex RS485 bus and how to manage direction signal

Started by pozz in comp.arch.embedded3 years ago 8 replies

Each node on the half-duplex RS485 bus should start transmitting only if all the other nodes are receiveing (their transmitters are all...

Each node on the half-duplex RS485 bus should start transmitting only if all the other nodes are receiveing (their transmitters are all disabled). Usually the bus is master-slave with the master sending a frame request to a single slave and the slave send back a frame answer. In this scenario, slave must be sure to start transmission of the answer after the master has disabled its transm...


DeviceNet and ASi stack recommendations.

Started by Les Cargill in comp.arch.embedded7 years ago 3 replies

Who's good? Target is Linux 2.6.x with plenty of RS485 UARTS and Intel 82527 CAN controllers. -- Les Cargill

Who's good? Target is Linux 2.6.x with plenty of RS485 UARTS and Intel 82527 CAN controllers. -- Les Cargill


Serial To Ethernet Converter

Started by QwertyBel in comp.arch.embedded13 years ago 5 replies

I need to remote RS232/RS485 signal over ethernet infrastructured network, which kind of device do you suggest me?? thanks a lot Bel

I need to remote RS232/RS485 signal over ethernet infrastructured network, which kind of device do you suggest me?? thanks a lot Bel


How would you do radio data links?

Started by Tim Watts in comp.arch.embedded10 years ago 7 replies

Hi, Quick intro - I'm a linux progammer/sysadmin. I play with AVRs (ATMegas mostly) for fun and have got on well with them. I'm looking to...

Hi, Quick intro - I'm a linux progammer/sysadmin. I play with AVRs (ATMegas mostly) for fun and have got on well with them. I'm looking to set myself a moderate project next year which is to do with home automation (thermostats etc). Although I *could* use RS485, CAN or some other wired links, I rather fancy playing with radio for the educational value. So I'm after something that...


which 8-bit micro

Started by Kim in comp.arch.embedded16 years ago 23 replies

I'm need a micro with following requirements: UART - RS485 inputs = 4 outputs = 4 Also need to drive a seven segment LED or dot matrix. Its...

I'm need a micro with following requirements: UART - RS485 inputs = 4 outputs = 4 Also need to drive a seven segment LED or dot matrix. Its for an remote operator station and the quantity is quite small, but may go to 1000 units over time. Its been awhile since my last project, so I'm not sure whats available today. Would prefer an "all-on-board" chip if possible. Cost is a considera...


RS485(Full Duplex)control signal question

Started by Anonymous in comp.arch.embedded12 years ago 1 reply

regards: If my system is like the followings: the system architecture is: http://0rz.tw/d83qm then do I need any control...

regards: If my system is like the followings: the system architecture is: http://0rz.tw/d83qm then do I need any control signal to control the "TX" "RX"? any positive suggestion is welcome. best regards to you all mike