modbus RTU protocol datatypes

[shubhlaxmi22]

Hello,

          I am using ADAM series with Modbus RTU protocol.which data type should i use for read and write operation?

[unclebump]

We need to know what ADAM module you are using. Does it have digital input/outputs, or is it an analog input/output?? If it is digital, you would use the discrete modbus functions(modbus functions 1,2). If it is analog, you would use the register functions(modbus functions 3,4)

[shubhlaxmi22]

I am using ADAM series 4019,4055,4024,4520.In my application analog signal change to digital.so which data type should i use?how to detect device through Labview?

[unclebump]

You will need to read holding registers to get the analog data. But the modules also have some alarming done with discrete coils. Look at Appendix H in the manual here.

http://support.advantech.com.tw/Support/DownloadSearchByProduct2.aspx?keyword=ADAM-4019&ctl00_Conten...

These devices connect to an RS485 network. I would also download the NI modbus library.

http://sine.ni.com/nips/cds/view/p/lang/en/nid/201711

Modbus is a master/slave setup. The master(computer) will write a command to the slave. The slave(ADAM) will respond with the data requested. Your labview code will need to poll these devices. periodically.

[shubhlaxmi22]

Does this Modbus Library support to labview 8.5?How to detect particular device number to get input n labview?

[RavensFan]

The ModBUS library will work in LV 8.5.  You may need to resave the library files once you open them in LV 8.5.

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shubhlaxmi22 wrote:
How to detect particular device number to get input n labview?

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Not sure what you mean by this.  You will need to know the slave address of your device and enter it appropriately in LV as a constant when you use the ModBUS subVI's.

[shubhlaxmi22]

Thanks for reply.I am able to do communication with digital signal.how do communicate with analog signal?which data type should use?

[unclebump]

You should use read holding registers to get the 40xxx data values.

[shubhlaxmi22]

Hello Sir,

                I got success in analog communication but register value which i get in software what should it indicate?4019 device is analog i/p device and my thermocouple instrument is connected to vin0+ and vin0-.how do i get value from that instrument?

[TV_Enable]

Hi shubhlaxmi22,

Could you please attach an image of your block diagram as well?  This will help me understand your current programming scheme.  Thank you in advance.

Regards,

Todd V.

Applications Engineer