error timed out when using Unit-test client and server example (RTU over RS-485)

[ghost]

I'm using version 3.1.1 and my two devices are two Linux systems running Centos OS. the physical connection is 2 wire half-duplex RS-485 connection, using modpoll i could get response using same parameters, but with libmodbus i cannot

So the code is basically the same as the Unit-test example. except i added

if (use_backend == RTU) { modbus_set_slave(ctx, SERVER_ID); modbus_rtu_set_serial_mode(ctx, MODBUS_RTU_RS485); modbus_rtu_set_rts(ctx, MODBUS_RTU_RTS_UP); }

to both the client and the server...

this is the error i got from writing single coil..

Opening /dev/ttyS2 at 9600 bauds (N, 8, 1) \ UNIT TESTING **

TEST WRITE/READ: [11][05][01][30][FF][00][8F][59] Sending request using RTS signal Waiting for a confirmation... ERROR Connection timed out: select Bytes flushed (0) 1/2 modbus_write_bit: FAILED [root@localhost tests]# ./unit-test-client

does anyone know what i did wrong?

thanks very much

[stephane]

The RS485 mode of Linux kernel is certainly misleading and it was finally not a good thing to support this Linux kernel option because it seems only one device in the world support it! You must certainly remove modbus_rtu_set_serial_mode(ctx, MODBUS_RTU_RS485); and adjust the response timeout (see Web doc or manual pages).

Please, could you ask you question on mailing list? Issue tracker is reserved for bug reports.

[ghost]

Thank you Stephane for replying,

but my Serial Port is using data + and data - lines sending data differentially, why is it misleading to have RS-485 mode for Linux Kernel?

i don't understand.

thank you very much

On Wed, Nov 13, 2013 at 3:38 PM, Stéphane Raimbault < notifications@github.com> wrote:

The RS485 mode of Linux kernel is certainly misleading and it was finally not a good thing to support this Linux kernel option because it seems only one device in the world support it! You must certainly remove modbus_rtu_set_serial_mode(ctx, MODBUS_RTU_RS485); and adjust the response timeout (see Web doc or manual pages).

Please, could you ask you question on mailing list? Issue tracker is reserved for bug reports.

— Reply to this email directly or view it on GitHubhttps://github.com/stephane/libmodbus/issues/161#issuecomment-28445607 .

[ghost]

so even after remove RS485 mode and i set the response timeout to 10 seconds, 100 seconds, 5 seconds,, or 1 second.. still giving me the same error.

is there something else that might be wrong?

thank you very much Stephane.

On Wed, Nov 13, 2013 at 3:38 PM, Stéphane Raimbault < notifications@github.com> wrote:

The RS485 mode of Linux kernel is certainly misleading and it was finally not a good thing to support this Linux kernel option because it seems only one device in the world support it! You must certainly remove modbus_rtu_set_serial_mode(ctx, MODBUS_RTU_RS485); and adjust the response timeout (see Web doc or manual pages).

Please, could you ask you question on mailing list? Issue tracker is reserved for bug reports.

— Reply to this email directly or view it on GitHubhttps://github.com/stephane/libmodbus/issues/161#issuecomment-28445607 .

[ghost]

Hi

how do i adjust when the RTS is on or off?. is it just default to 1ms on and then 1ms off?.

thank you

On Wed, Nov 13, 2013 at 3:38 PM, Stéphane Raimbault < notifications@github.com> wrote:

The RS485 mode of Linux kernel is certainly misleading and it was finally not a good thing to support this Linux kernel option because it seems only one device in the world support it! You must certainly remove modbus_rtu_set_serial_mode(ctx, MODBUS_RTU_RS485); and adjust the response timeout (see Web doc or manual pages).

Please, could you ask you question on mailing list? Issue tracker is reserved for bug reports.

— Reply to this email directly or view it on GitHubhttps://github.com/stephane/libmodbus/issues/161#issuecomment-28445607 .

[fatalfeel]

i test one side is ubuntu 14.4 PC unit-test-client another side is android dev board. unit-test-server i meet this problem too. finally i change hardware and use the usb to rs485 serial on both side Bus 003 Device 010: ID 1a86:7523 QinHeng Electronics HL-340 USB-Serial adapter test all pass

[adgnaf]

@fatalfeel Thank you for sharing experience. But the origin purpose is to communicate over native rs485 port instead of a usb-rs485 adapter.