STR 571 Modbus

[user14395]

I am having trouble with the STR571. I want a computer to read via Modbus the value the STR571 has read.
(The STR571 reads on its master port from a pressure sensor, that part goes well)

The command I send is:

Code: Select all

F003 03E8 0002 515A

(Address 240; FC 03 ; Data Address 1000; 2 Words; CRC)

I am getting no answer.
What could I be doing wrong?

[Pixsys tecnico 6]

Hi,
which COM port are you using? And the Baud rate....

Set the COM port number 2 properly. (User manual paraghaph 13.8) and use the STR PIN 8 and 14 with RS485. Check the electrical wire connection of the RS485 (PIN 8 = B+ and PIN 14 = A-)

Best Regards

[user14395]

Hello!

The computer is a panel PC where the RS485 port is COM 8 (it's a optional extra card for that Panel PC). We tested the signal from the PC and we can see the signal from the PC going on the wires A and B. We'll check again for a possible inversion between A and B, but I think I remember we tested both ways already, just to be sure.
We didn't connect the ground wire on the STR571 side though, is it necessary? Also, do you need the end resistor for the RS485? We saw the connection between the STR571 and the sensor didn't really need it.

We tried the default baud rate (57600) as well as a more usual 9600. At the moment, it still is set to 9600.
We also tried 8n2 as well as the default 8n1 of the STR571.

Another question I have (as I haven't received an answer from the STR571 I don't know yet) is:
The data on address 1000, is the exact data read from the sensor or is it already modified by the offset/span we set in the STR571? I'm guessing it's the first, but I'd like to know for sure so I can go forward with the programming of the computer.

Best regards and have a nice week-end,

[Pixsys tecnico 6]

Hi,
the RS485 ground connection and the resistor for the RS485 is not necessay, but if your RS485 wire connection is very long you need it.

The data on address 1000, is the exact data...have you try read the address 1001,1002,1003...?

Best regards.

[user14395]

Hello,

We brought the reply delay up to 10ms, that seems to have done the trick, we now have an answer.

To copy the configuration unto other STR571, can we use any USB card or must we use the specific one sold by Pixsys?

Best regards,

[Pixsys tecnico 6]

Hi,
you can use the micro-USB memory (code 2100.30.013).

http://www.pixsys.net/en/products/softw ... mory-cards

Best regards.

[Pixsys tecnico 1]

Hi,
if you have an android smartphone with NFC antenna, you can also use our Mypixsys App to configure/clone parameters on STR series:

http://www.pixsys.net/en/products/softw ... ppmypixsys