Hello Stefan,
I just tried your patch below and found it fixed my previous problem with
segfaults when the modbus module was enabled. This was with collectd
5.0.2/libmodbus 3.0.1 on i386. Thankyou!
I am though now seeing a slightly odd situation where after a period of time
all data points that are collected via the modbus module are reported as zero.
Other collectd modules are still collecting correctly. A restart of collectd
fixes the problem for awhile, but then it occurs again. I don't think it's a
connectivity to the modbus device issue as it occurs after a few hours.
Using 'rrdtool dump' I can see the logged values for the time periods and
<last_ds> both reported as zero.
I need to recompile with debugging enabled to see if I can track down the
problem but I was wondering if you had seen anything similar?
Cheers,
Matt
> Hi all,
>
> I also stumbled across the modbus segfault (collectd 5.0.1 / libmodbus 3.0.1
> / gentoo, both i386 & x86_64).
>
> The problem is that host->connection is simply never initialized in
> mb_read_data() before being passed to libmodbus.
> The only place mb_init_connection() is called is from within the reconnection
> loop below.
>
> Adding this before the call to modbus_set_slave() makes the crash go away:
>
> if (host->connection == NULL)
> {
> status = mb_init_connection (host);
> if (status != 0)
> {
> ERROR ("Modbus plugin: mb_init_connection (%s/%s) failed. ",
> host->host, host->node);
> return (-1);
> }
> }
>
> As I'm reading float values I also had to modify mb_register_to_float() to
> get what I was expecting.
> But not sure whether this is due to running on a 64bit machine or just my PLC
> being backwards.
> What I'm doing is
>
> static float mb_register_to_float (uint16_t hi, uint16_t lo) /* {{{ */
> {
> union
> {
> uint8_t b[4];
> uint16_t s[2];
> float f;
> } conv;
>
> #if BYTE_ORDER == LITTLE_ENDIAN
> conv.s[0] = hi;
> conv.s[1] = lo;
> #else
> ...
>
> --
> Cheers, Stefan
> _______________________________________________
> collectd mailing list
> collectd@verplant.org
> http://mailman.verplant.org/listinfo/collectd
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