I have a question about the VlvAnL block from the APL. I would like that the operator can determine by faceplate the specification for the MV (external or internal). But, as far as I can see, the MV is always in external during automatic mode and in internal during manual mode. The selection for the specification of the MV is always gayed out in the faceplate. Is there a way to let the operator decide it independent from the mode?

I have set MV_LiOp to 0 and all Operator Permissions are 1. I'm using PCS7 V9.0 SP2.

DDo84

I have a question about the VlvAnL block from the APL. I would like that the operator can determine by faceplate the specification for the MV (external or internal). But, as far as I can see, the MV is always in external during automatic mode and in internal during manual mode. The selection for the specification of the MV is always gayed out in the faceplate. Is there a way to let the operator decide it independent from the mode?

I have set MV_LiOp to 0 and all Operator Permissions are 1. I'm using PCS7 V9.0 SP2.

 Dear DDo84, 

It is because you have locked the XXLiOp by forcing an input of "1". 

there are SP_LiOp and ModLiOp. these two inputs are to control whether an operator can configure internal or external/auto or manual at HMI. 

Based on my experience of using PID, I always prefer operator /supervisor could do some intervention at the HMI in case something goes wrong during the process. I would prefer, when process start, 

When process start

1. PID block - set a 2s pulse to ModLiOp and SP_LiOp =0->1->0 and SP_ExtLi =1, AutoModLi=1, MV_ForOn=1 and MV_Forced = minimum MV%. for xx seconds (or condition met, stable flow, stable pressure, stable temp). 

2. PID Block - Release the MV_ForOn = 0. 

During the Process 

3. Connect the VlvAnL ManAct or with VlvAnL Failure/bad to MV_TrackOn of PID block. Connect the VlvAnL RbkOut to MV_Trk. When VlvAnL set to Manual from HMI, the RbkOut of the VlvAnL will be sent to PID. The MV_TrackOn will get the current VlvAnL value. VlvAnL remain Auto and external, as the MV of the PID will send the current Rbk to VlvAnL. 

Stop the Process, 

4. There are many ways of doing it. 1st , change the external setpoint to lower. 2nd way, use MV_ForOn. 3rd way, just stop the source (pump, heater), wait for a period, set the PID to initial condition and close the valve directly. 

For interlock, when something unexpected issue come, you may set the MV_TrackOn to 1, or you may use MV_ForOn to set a percentage to MV_Forced. 

Hope this could help you. 

Dear JazTai,

Thank you for your reply.

Regarding the ModLiOp and MV_LiOp on the VlvAnL block, I have forced them both to 0. With these settings in my application, the operator can determine the operation mode of the block but cannot determine the specification (internal or external) for the MV. The MV is always in external when the mode is set to Automatic and in external when the mode is set to Manual, so it looks like the mode determines the specification of MV. Is this a feature of the VlvAnL block?

Based on the APL manual (see attachment) I would say that the operation mode and specification of the MV are separately configurable.

Regarding your explanation about your way of implementing a PID blocks, can you send me an example of it?

Thanks in advance!

 Regarding the MV_LiOp issue, can you upload a picture on your faceplate as well as the CFC logic, function block IO in Online mode? 

Based on my understanding, if you have Mod_LiOp, you can select the "Auto/manual" Mode and if you have MV_LiOp,  then you can configure MV external or MV internal. Since VlvAnL has these inputs, you should be able to configure them separately. 

I have set up a quick chart from my existing project and attached a simple picture for you. The most important key is the concept of controlling the PID which I have mentioned in a previous thread. If a certain part you do not understand, you may always point to that particular sentences, I will do even more detail explanation. 

Hope you find this useful for you.  

Dear JazTai,

Thank you for your reply. Very usefull!

In the attachment you will find the requested screenshots. I hope these will indicate the problem.

Dear DDo84, 

What is your library version? I think you might consider an upgrade on your library and faceplate first before doing troubleshooting. 

Software Updates

look for / search for advanced process library. 

take a picture on your feature bit too. 

Hi DDo84,

if you don't use a auxiliary valve, you can't use the internal manipulated variable in the automatic mode (see the manual PCS 7 Advanced Process Library at section VlvAnL modes).

If you want to use the internal manipulated variable in the automatic mode you have to activate the feature bit 5.

With regards
Heisenberg