PLC and HMI question... 1

[physicshack]

Hello

I am using a Rievtech PLC and a Wecon HMI to log data for a customer I am making an automated test rig for. the issue is that I am trying to use their existing pressure, flow and power transducers that are already powered to obtain an input to the PLC. The Reivetech (PR-18dc-da-r) has a common ground (-ive) connection that clearly these transducers dont share. Infact the input power to the transducers is not the same as the supply to the Rievtech PLC. I am confused how this can be wired up to use the 0-10V output from the transducers in this case. any help would be greatly appreciated.

The other question i have is with the HMD. Its a Wecon 700E. WHat I need is to show the instantaneous performance point on a graph (which is no problem) however I would like this displayed next to the expected performance in pressure and flow. I can not see how I can use a table of data or table or readings to generate a cureve on this HMI. again, any advise on this would be amazing.

Many thanks

David

 

[danw2]

To eliminate the common mode voltage between the signal grounds, you need to buy an DC-to-DC voltage isolator for each of the signal channels. The isolators are powered, so the isolator you use must be have 3-way isolation, power supply, isolated from input and output, input and output isolated from each other.

Most isolators are single channel, but there are two channel models available. Here's a link to a variety.

https://api-usa.com/4380.php

Wire the source voltage signal in parallel to the input of the isolator and then wire the isolator's voltage output signal to the Rievtech PLC AI.

I can't help you with the HMI graph/chart/trend, but I'd search for each of the those terms in the HMI documentation.

 

[physicshack]

Hello Dan

That is really helpful thank you. I have an ANU device that i am using to simulate a 0-10 signal for my testing. The ANU has an auto mode that takes an input and then relays the signal. the only issue is it still uses a common ground so I guess what you are suggesting is essentially what I have in the ANU but with comletely different input and outputs.

Thanks for the info... I now konw what to look for

 

[danw2]

Yes, an isolator reads the signal on its input side and re-transmits it on its output side, but without any galvanic (electrical) coupling between input, or its power supply. Your problem is not an uncommon problem; there are lots of isolator vendors; lots of choices.

After re-reading your issue with expected performance, I doubt my suggestion will help. Trend and chart are typically terms for display of logged data values over time (Y-t). It appears that you need to find an expected performance value from a temperature vs pressure table.

 

[Macbeth]

You need a signal Splitter.
Samples:
1.Input:0-5V Power Supply:24V Output:two 4-20mA Type No.: DIN12 IAP- V1-P1-A4
2.Input:0-10V Power Supply:24V Output:0-10V/4-20mA Type No.: DIN12 IAP-V2-P1-V2A4
3.Input:4-20mA Power Supply:24V Output:two 4-20mA Type No.: DIN12 IAP- A4-P1-A4
4.Input:0-10V Power Supply:24V Output:two 0-10V Type No.: DIN12 IAP V2-P1-V2

You could attempt to connect in parallel, although some "Meter Loading" will occur. Connect your DC-Comm to M and tap off the signal to the V1 Input terminal of your PLC.

For trending only HMI that I have seen with X-Y function is "TrendX"