Hi,

just for reference and to help future questions:

I am running OpenHAB on a dedicated RasPi. It is a Java application which I do not want to run on a Neuron. Keep it simple and stupid.

In C code it was not too complicated to get data from OpenHAB though curl calls.
See code snipplet:

/* Function gets calledd with an item name          */
/* The url is defined here globally:                */
/* url="http://openhab.domain.com:8080/rest/items/" */

long get_2file(char *url, char *filename )

{
CURL *curl_handle;
FILE *FI;

int r,code;

code = 0;
curl_handle = curl_easy_init();

/* set URL to get here */
curl_easy_setopt(curl_handle, CURLOPT_URL, url);

/* disable progress meter, set to 0L to enable and disable debug output */
curl_easy_setopt(curl_handle, CURLOPT_NOPROGRESS, 1L);

/* use default write function */
curl_easy_setopt(curl_handle, CURLOPT_WRITEFUNCTION, NULL);

/* open the file */
FI = fopen(filename, "w");
if(FI) {

        /* write the page body to this file handle */
        curl_easy_setopt(curl_handle, CURLOPT_WRITEDATA, FI);

        /* get it! */
        r = curl_easy_perform(curl_handle);
        if (r != 0) {
                code=-1;
        } else {
                /* Data is now in the file */
        }
        /* close the header file */
        r = fclose(FI);
} else {
        code=-1;
}
/* cleanup curl stuff */
curl_easy_cleanup(curl_handle);

return code;
}

@all

As I was struggling again with this I figured it out now finally (at least I hope so).

My issue was the interpretation of whatever value I got.

So for alle future readings:

In the linked Calc-Sheet above you have notes about the registers (read only registers, not bits!).

So for the M103 you have the "Registers - group 1" and "Registers - group 2". Use these. The coils tables are somehow misleading (at least for me).

Additionally be aware modbus_read_registers() need to write the data into an uint16_t variable. With the help of @ntd and his suggestes "union" I was easy to "convert" them into the uint32_t. Unions access the same memory by different variables. See more here.

In the code sniplet above modbus_read_registers() writes the content into the counter.word memory location and the prinft reads them as uint32_t. Easy going now to re-calculate the counter.dword variable to get the values you need.

So to read the current settings and values of all relays and digital inputs I use the following code:

uint16_t state;
union {
        uint16_t word[2];
        uint32_t dword;
} counter;


/* Relais */
modbus_read_registers(modbusglob,101,1,&state);
printf("Lesen Relay Register: %u\n",state);
printf("\n");

/* DigitalIN 1 */
modbus_read_registers(modbusglob,0,1,&state);
printf("Lesen DigIn1: %u\n",state);

printf("\n");
/* Digital-In 1 Counter */
for (i=8;i<16;i=i+2) {
        modbus_read_registers(modbusglob,i,2,counter.word);
        printf("Counter %d DigIn1: %u\n",i,counter.dword);
}
printf("\n");

/* DigitalIN 2 */
modbus_read_registers(modbusglob,100,1,&state);
printf("Lesen DigIn1: %d\n",state);
printf("\n");


/* DigitalIN 2 Counter */
for (i=103;i<118;i=i+2) {
        modbus_read_registers(modbusglob,i,2,counter.word);
        printf("Counter %d DigIn2: %u\n",i,counter.dword);
}

This works now perfectly.

/KNEBB

@knebb
Answering myself as I figured it out by try&error. Use address 2. Use values from 0 to 4096 (as documented).

However, I measured the AO port and never came above 8V (with 4096) with default settings (did not change any of Vref, Vrefint, Voffs, Vdev). Is this measurement issue or something wrong with my code?

/KNEBB

Hi all,

I am on the way in using the C library modbus to read/write to my Neuron M103.

I have a question regarding the documentation:
Here it writes about the calculation of the value to be set for the desired voltage.

Now I checked the Register Docs and found two addresses:
      2  Analog Output (raw value) as Obsolete
3000 Analog Output value as Basic

So would I write to address 2 using the calculated value?
Or woud I use the desired voltage (0-10) to write to address 3000?
Or calculate and write to 3000?

Thanks!

/KNEBB

@ntd

Sorry to bother you. I think I got it finally!
Using modbus_read_bits will read nb bits and write (according to the state) 0 or 1 into dst[0]...dst[nb].
I had thought when reading 4 bits it will write the first state into the first bit of dst, second into the second and so on.

But no, it writes the state as 0 or 1 into each of the uint8_t .

I was successfull in reading RO2.8 and DI2.1 together with

int nb,i;
uint8_t dst[2];
nb=2;
modbus_read_bits(modbus,107,nb,dst);
for (i=0;i<nb;i++)
{
  if (dst[i] != 0) 
  {
    printf("Bit %d is %u\n",i,dst[i]);
  } else {
    printf("Bit %d is %u\n",i,dst[i])
  }
}

And in case RO2.8 is on an DI2.1 is off I will get:
Bit 0 is 1
Bit 1 is 0

Similar this would apply to modbus_read_register();

Holy sh**, I think I really got it now!

Thanks for your patience!

/KNEBB

@ntd
Perfect!

Got it finally. I mixed up modbus_read_bits and modbus_read_register. Now working like a charm!

Thanks a lot!

/KNEBB

Thanks for the explanation; I figured it already out Raspbian is littleEndian.

Just to make sure:
To read i.e. the counter for digital input 2.1 (address 103-104 with DWORD, 32bit in total) I would use:

uint8_t counter[4];
modbus_read_bits(bus, 103, 4, counter);

Or this one?

uint8_t counter1[2],counter2[2];
modbus_read_bits(bus, 103, 2, counter1);
modbus_read_bits(bus, 104, 2, counter2);

Would both work?

Sorry for my dumb question, I am really new to modbus...

/KNEBB

@ntd :Thanks a lot four your input, I really appreciate it.

I am just wondering as there seems to be no difference between uint8_t, uint16_t and uint32_t.

See my question here.
When using uint8_t the result is exactly the same. All seem to be 32bit long...

So how does modbus deal with this? It writes only the least significant 8 bits? Others are set to zero?

/KNEBB

Hi,

as I am currently coding my application and I am unsure about electronics. Would the following work for testing purposes? To see the DI changes when DO is set ON? Or is this a really bad idea?

Thanks a lot!

/KNEBB

Hi all,

ok, I manged to use the relays through modbus with libmodbus with my C-code. Now I am trying to use the DI/DO/AO/AI interfaces.

I see the Neuron Registers Map but I am only able to understand it partially...

I am aware the function modbus_read_bits() can be usedd to read the DIs. So I open a modbus_tcp connection with the address of DI2.1 for example:

modbus_read_bits(modbus_handle, 108, nb, *dest);

*dest is supposed to be uint16_t.

I was able to read the above- finally I have some data in *dest. But how do I have to read the data there? I expected something like "bit 1 tells if the DI is currently ON or OFF and bit2 is the counter while writing bit3 will reset the counter" or stuff like this.

So I am a little bit lost here to interpret the values I got.

Nearly the same is for writing. What values should I put into uint16_t to enable the DI?

And how can I configure the AO?

Thanks a lot for hints!

/KNEBB