building a function "modbus udp"

2010/6/5 Steven Hsu <email address hidden>:
> New question #113582 on libmodbus:
> https://answers.launchpad.net/libmodbus/+question/113582
>
> I would like to add a UDP transfer function instead of the default TCP, can I just follow the code format inside modbus.c and modbus.h or need to modify many other files? thanks.

Take care to use the source code from github and yes, for now, you
only need to edit modbus.[ch] to do that.

Thanks for your quick response.

I spent whole night try to modify the source code and the confilct between tcp and udp, also the bandwidth-master.c, bandwidth-slave-many-up.c under tests folder. But ...It seems like the modbus client cannot receive the packet from other modbus server (I used tcpdump to monitor the packet and check the firewall or route problem) but success in localhost but the slave shows "the Illegal data address XXX in read_holding_registers".

I copy the function structure of tcp for the udp function, comment the code that udp wont need (like accept and listen) but infact I'm not very familar with it ...
I think maybe libmodbus can impliment such function inside the origin program.

http://163.22.32.100/~sintsu/libmodbus-udp.tar

Could you provide a patch for review or a git branch please?

2010/6/6 Steven Hsu <email address hidden>:
> Question #113582 on libmodbus changed:
> https://answers.launchpad.net/libmodbus/+question/113582
>
>    Status: Answered => Open
>
> Steven Hsu is still having a problem:
> Thanks for your quick response.
>
> I spent whole night try to modify the source code and the confilct
> between tcp and udp, also the bandwidth-master.c, bandwidth-slave-many-
> up.c under tests folder. But ...It seems like the modbus client cannot
> receive the packet from other modbus server (I used tcpdump to monitor
> the packet and check the firewall or route problem) but success in
> localhost but the slave shows "the Illegal data address XXX in
> read_holding_registers".
>
> I copy the function structure of tcp for the udp function, comment the code that udp wont need (like accept and listen) but infact I'm not very familar with it ...
> I think maybe libmodbus can impliment such function inside the origin program.
>
> http://163.22.32.100/~sintsu/libmodbus-udp.tar
>

I don't have time to review your code but I've made major changes in
the code this summer to ease the implementation of multiple backends
(only RTU and TCP for now). Could you rebase your UDP code on master
branch and create an UDP backend, please?

The best way to do this, it to create a fork of my master branch on
github (a branch called udp for example) and to apply small and atomic
commits to your branch, so it will be easier for me to review your
code and merge your branch.

Stephane

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