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Equipment Help in SA Templates

Chris

I'm currently configuring a new system and need a little advice. I am using the SA templates and have run into a cross roads. Let's start with the simple Meter, this make complete sense when you have a single element analog value with a single PV. But what if you have a dual element RTD, how would you configure this. A Meter type instance for each RTD element (A and B)? How would the selected or averaged value be handled as it's own PV? What if the averaged value is the only one that has the LL L H HH alarms, and even a high difference and other custom alarms?

It seems like with the example above, I would need 3 Meter type instances, two for each element and one for the averaged value and it's custom alarms. How would you tie them together in the project so the the trend window in the info pane shows all three PVs?

TIA.

Chris

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  • Bradley, thanks for the very detailed reply.

    It does get a bit more complicated.

    Answers to your questions,
    1. Basically yes, the RTD (lets call it TE_101) in my example is a single temperature measurement with two elements, A and B. The additional info we need is an alarm for the A and B elements is the sensor failed alarm(one for each element).

    2. The PV of TE_101A, TE_101B, TE_101SEL should all be seen on the page. In some cases it could be TE_101A1, TE_101A2, and TE_101SEL. The reason that there is sometimes a slight difference in the suffix of the elements is because there are cases in which two dual element RTD sensors are used. In that case, it would be TE_101A1, TE_101A2, TE_101B1, TE_101B2 and TE_101SEL. This is rare but cases still occurs for time to time. I would probably just use a different equipment meter type for the differing scenarios.

    3. For the individuals elements, they only have a senor fault alarm. The "SEL" PV is normally averaged(only if the A and B difference is below a certain theshold) in the controller and has PLC limit alarms applied to it. Its called SEL because it is the Selected PV in the control being used as the most trusted PV for the application. The controller has a High Diff alarm between the elements too, when this occurs, it could select the highest or the lowest element PV, again depending on the application. Oh, and to add even more complexity to this, the SEL PV may only have H and HH alarms, OR L and LL alarm but not both usually.

    I have already setup my project to use PLC alarm limits, that all we use. In cases where we may only need a low alarm, we just set the low low limit to the zero EU value in the PLC.

    Your reply has a wealth of information in it and I hope to work out my issues from this point. There are many other challenges ahead on this project, so I'll probably be asking more questions.

    Thanks again,

    Chris
Reply
  • Bradley, thanks for the very detailed reply.

    It does get a bit more complicated.

    Answers to your questions,
    1. Basically yes, the RTD (lets call it TE_101) in my example is a single temperature measurement with two elements, A and B. The additional info we need is an alarm for the A and B elements is the sensor failed alarm(one for each element).

    2. The PV of TE_101A, TE_101B, TE_101SEL should all be seen on the page. In some cases it could be TE_101A1, TE_101A2, and TE_101SEL. The reason that there is sometimes a slight difference in the suffix of the elements is because there are cases in which two dual element RTD sensors are used. In that case, it would be TE_101A1, TE_101A2, TE_101B1, TE_101B2 and TE_101SEL. This is rare but cases still occurs for time to time. I would probably just use a different equipment meter type for the differing scenarios.

    3. For the individuals elements, they only have a senor fault alarm. The "SEL" PV is normally averaged(only if the A and B difference is below a certain theshold) in the controller and has PLC limit alarms applied to it. Its called SEL because it is the Selected PV in the control being used as the most trusted PV for the application. The controller has a High Diff alarm between the elements too, when this occurs, it could select the highest or the lowest element PV, again depending on the application. Oh, and to add even more complexity to this, the SEL PV may only have H and HH alarms, OR L and LL alarm but not both usually.

    I have already setup my project to use PLC alarm limits, that all we use. In cases where we may only need a low alarm, we just set the low low limit to the zero EU value in the PLC.

    Your reply has a wealth of information in it and I hope to work out my issues from this point. There are many other challenges ahead on this project, so I'll probably be asking more questions.

    Thanks again,

    Chris
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