Here is the actual error report back from terminal: ValueError: Checksum error in rtu mode: '\x01x' instead of '|\xa3' . The response is: '\x00\x01\x06\x00\xff\x00\x01x' (plain response: '\x00\x01\x06\x00\xff\x00\x01x')
On Sunday, July 5, 2015 at 4:20:48 PM UTC-4, A W wrote: > > Ok...I seems to got it working after configuring the GPIO pin for RTS. > However, when I tried to communicate with modbus device, it gives me an > "Checksum error in rtu mode". I am using minimal modbus library, and my > code works fine when communicating between windows and my device. > > I have tested my connection with the scope and it seems to get getting the > correct output > > > > <https://lh3.googleusercontent.com/-F3TXY-EePnE/VZmQRb1SiZI/AAAAAAAAAFA/3WE1rRaXQis/s1600/tek00001.bmp> > > > When testing it with the minimal modbus library, the slave ID, function > code and payload data is correct. It just seems to have problem getting > pass the error check. > > > > <https://lh3.googleusercontent.com/-e-xK1jzwGAM/VZmQk-l6ZrI/AAAAAAAAAFI/jGzceziRmiI/s1600/test3.py_write_reg255.bmp> > > > I have configured my baud rate and parity check correctly, but I can't > seems to figure out why it's giving me this checksum error. Anyone have any > ideas where the problem is? > > > On Saturday, July 4, 2015 at 6:29:11 PM UTC-4, A W wrote: >> >> Hello, >> >> I came across this tutorial on configuration for RS-485 serial >> communication, but I am new to this and I need some clarifications on the >> procedure. >> >> My beaglebone black is currently running on the latest Debian image >> >>> >>> Linux beaglebone 3.8.13-bone70 #1 SMP Fri Jan 23 02:15:42 UTC 2015 >>> armv7l GNU/Linux >> >> >> >> >> On the website >> http://inspire.logicsupply.com/2014/09/beaglebone-rs-485-communication.html >> >> Let's dive into the Kernel a bit to to see how RS-485 works in Linux; the >>> standard steps to put a UART into RS-485 mode are: >>> >>> 1. Open the special tty file >>> 2. Create a serial_rs485 struct and set the desired configuration >>> values >>> 3. Pass the configured struct to Kernel driver by using ioctl >>> <http://man7.org/linux/man-pages/man2/ioctl.2.html> on the open >>> serial port file descriptor >>> >>> I don't understand do these steps, where do I find the special tty file >> and as well as creating the serial_rs485 struct. Can someone guide me >> through this part? >> >> Thank you. >> >> >> > -- For more options, visit http://beagleboard.org/discuss --- You received this message because you are subscribed to the Google Groups "BeagleBoard" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
