Endress+Hauser Flow Meter

Hi,

I have a Endress+Hauser Flow Meter (Modelrowirl 72F). In the technical Details sheet it shows some details on Communication, What do you mean by that? I normally use 4...20mA Output, which will be connected to a PLC. The below are the given details...


Communication:

HART
PROFIBUS PA
FOUNDATION Fieldbus


Outputs:
4...20mA
Pulse/Frequency
Status

Ya the question is, how this communication facility is going to help me?

The comms buses provide additional data as well as an element of control for example remote reset of totalizer or empty pipe detection. You can also return various values from the flowmeter (Volume flow, calculated Mass flow, corrected Volume flow, Totalizer)

If your norm is to use the 4-20mA i dont see the point in changing it unless you already have a bus running through your instrumentation network.

Thanks.
By using this communication can the flow meter directly talk to SCADA bypassing PLC/Controller?

Hart, Profibus PA and FF are normally used in large or very large process plants.

In stead of checking and setting up devices locally at the device (which in a large plant could require a walk of 1 km for example), you do it centrally from the control room.
Another advantage with the mentioned fieldbusses is the savings in cabling, which can be immense for very large plants.

If you only have a small plant, then the mentioned fieldbusses would be overkill.

Thanks.
My doubt is, by using this communication can the flow meter directly talk to SCADA bypassing PLC/Controller?

Yes you could, but why ?
A SCADA is just a display for the process. It does not (should not !) in itself control anything.

In larger process control systems, the PLC and the SCADA melts together so you cannot talk of only the SCADA without the other.

Jesper, I'm only interested in recording the Flow meter readings(saving in a database), no controls. If I can avoid the PLC it would save me some cost.

You need to get the signal into your system somehow, no matter if its 4-20mA, Hart, PA, or FF. I dont think you will save anything.
You need either a PLC, or dedicated PC hardware for 4-20mA (with or without Hart), DP PA or FF. The cost will be almost the same.

Here is a manual describing using Hart with S7-300:
http://support.automation.siemens.com/WW/view/en/22063748

As you can see it is not trivial. Also, I think the Hart modules are not cheap.
Doing the same on a PC will not be easier or cheaper.
I expect DP PA and FF to be at least as difficult and expensive as Hart.

Hmmm. Got the bitter truth Thanks Man.

If you just want to watch the flow in a PC, you can use the FieldCare software from E+H (free)and buy an Hart Modem to connect the flowmeter to the PC, and you can view the Frequency, Flow and you can also change the flowmeter configuration.
Do you agree Jesper?
You can also use the Hart Modem for all future configurations.

HART
PROFIBUS PA
FOUNDATION Fieldbus

You only get one of the three above in any device.

HART is the same as 4-20mA. 4-20mA 'carries' the HART signal.

Any device that is already connected to your SCADA that has a 4-20mA input will take the 4-20mA flow rate signal for access to SCADA.

The advantage of the protocols is that data like the flowmeter's totalizer is available to SCADA. If you take the 4-20mA directly into some device that is SCADA connected and you want a total, SCADA would have to calculate the total from the flow rate.

Another advantage of using comms instead of 4-20 mA is the ability to eliminate wiring if the system has multiple transmitters with the same communications protocol availble. Rather than running separate twisted pair for every analog signal you can mulit-drop a single comm link and get all of the transmitter data at once, even if there are some flow meters and some pressure transmitters and some analytic instruments. Then all you have to do is provide power, which may be readily available from existing wiring. Valve actuators and VFDs and smart motor starters can be on the same comm link direct to SCADA or a PLC. Obviously you have to make sure you have redundancy or other contingency plans in place for loss of comms to critical equipment, and safety should never rely on a comm link, but the potential savings are significant and nowadays reliability is pretty good on communications.

As pointed out above, you can then also get lots of other data. For example many flow meters also take temperature readings, and those are available without additional wiring.

nonuke said:

If you just want to watch the flow in a PC, you can use the FieldCare software from E+H (free)and buy an Hart Modem to connect the flowmeter to the PC, and you can view the Frequency, Flow and you can also change the flowmeter configuration.
Do you agree Jesper?
You can also use the Hart Modem for all future configurations.

Click to expand...

I dont know the Fieldcare software you mention, but I guess it is a software package to setup and diagnose E&H devices via Hart. I guess then that you could use it as a remote monitoring on the cheap.
If it has to be integrated into a SCADA, then I suppose that it could be possible if there exists and OPC server for the Hart modem.
I dont have that much experience with Hart. Have only dabbled with it once, many years ago.

This is a cheap way to log 4-20 mA signals, I don´t believe is scada compatible.
http://www.microdaq.com/lascar/usb-current-logger.php