We've got a system running XP embedded, with COM2 being a hardware RS485 port. In my code, I'm setting up the DCB with *RTS_CONTROL_TOGGLE*. I'd assume that would do what it says... turn off RTS in kernel mode once the write empty interrupt happens. That should be virtually instant. Instead, We see on a scope that the PC is driving ...
Hi, I'm writing a RS485 driver for an embedded C project. The driver is listening for incoming messages and should notify the upper layer application when a complete message is received and ready to be read. What is the prefered way to do this? By using interrupts? Trigger a SW interrupt and read the message from within the isr. Le...
Hello all, I have searched diligently (both within the S[O|F|U] network and elsewhere) and believe this to be an uncommon question. I am working with an Atmel AT91SAM9263-EK development board (ARM926EJ-S core, ARMv5 instruction set) running Debian Linux 2.6.28-4. I am writing using (I believe) the tty driver to talk to an RS-485 seria...
Can someone suggest an open source implementation of a Modbus RTU Slave for a Microchip PIC18 processor? I'm looking for an implementation of Modbus RTU for RS-232/RS-485, but a Modbus TCP/IP implementation would be welcome as well. ...
My brain is fried, so I thought I would pass this one to the community. When sending 1 character to my embedded system, it consistently thinks it receives 2 characters. The first received character seems to map to the transmitted character (in some unkown way) and the second received character is always 0xff Here is what I observed: T...
I have a very low speed data connection over serial (RS485): 9600 baud actual data transmission rate is about 25% of that. The serial line is going through an area of extremely high EMR. Peak fluctuations can reach 3000 KV. I am not in the position (yet) to force a change in the physical medium, but could easily offer to put in a simpl...
I am writing a simple multi-drop RS485 protocol for serial communications within a distributed system. I am using an addressable model where slave devices are given a window of 20ms to respond. The master uC polls the connected devices for updates and they respond accordingly. I've employed checksums and take the necessary overrun pre...
I am attempting to connect and control a device which only accepts RS-485 input. I wish to communicate to this device via my existing UC3A1512. Does anyone have any existing source code or examples that may help me to create this interface? I need a method of outputting date via RS-485 format. I do not need to establish round trip co...