How Does OPC Server Report FP-AI-111 Data?

[pittpanther]

I have several mA FP-AI-111 I/O cards that will be communicating data through the OPC Server to an OPC Client. I have looked through the AI-111 manual and the OPC Server Online Docs, and have not been able to determine how the signal will be reported. For example, if 12.0 mA is the signal, will the OPC Server report this as 12 to the OPC Client, or since it has a 16 bit resolution, will it report it as 32768?

I would test this empirically but I do not have a mA/Voltage generator!

Thanks!

[Ben]

mA/Voltage geneator.

current (A) = Voltage (volts)/ Resistance (ohms)

12 mA = 12V/1000ohms

(8) 1.5 V batteries in series gives you 12 Volts.

Wire batteries in series with 1000 ohm resistor and put this in series with the FP input.

If you are on campus at pitt, the batteries and resistor should be in stock in the physics stock room. Tell Karl, Ben says hi.

Ben

[Aaron_G]

The OPC Server will publish the numerical value of "0.012" to the OPC Client. The OPC Server will always provide the EUV (Engineering Unit Value) rather than the Raw value (32768).

Regards,
Aaron

[pittpanther]

Thanks for the input Ben!

Unfortunately, I am not in Oakland (although I would love to be!) - I graduated a few years back!

I am doing some mass database entry in this 3rd party HMI package and just need to know how I should arrange the scaling.

[pittpanther]

Thanks Aaron - is there anyway to request the raw value from the OPC Server instead (my 3rd party HMI package handles raw values very well, and can handle the EUV, but not easily)?

[Aaron_G]

No, there is not. This is due to the differing nature of FieldPoint network modules. Some network modules do the scaling in the network module and publish the scaled values, while others publish the raw values and have the server do the scaling. Since the server either scales or doesn't scale, it does not have the ability to reverse scale a value.

Sorry,
Aaron

[pittpanther]

Which network modules perform scaling at the module level? We are using the FP-2000s.

[Aaron_G]

Acutally, you are forgetting to include the input impedance of the FP-AI-111 current inputs (100 Ohms). So using the example above would provide 12 Volts/1100 Ohms=10.9 mA. If you wanted 12 mA, you should use 900 Ohms.

Regards,
Aaron

[Aaron_G]

The simplified rule of thumb (as of July 2002) is serial modules require the server to scale the data and ethernet modules scale the data themselves.

Regards,
Aaron

[pittpanther]

Forgive my thickheadedness, but does that mean that the FP-2000 scales the data itself? If so, does that mean it will report the data to the OPC Server in EUV (i.e.: 0.012 for 12mA), or Raw Units (i.e.: 32768 for 12mA)?