Hello,

I am using a TP700 comfort panel with a s7-1200 PLC

I am trying to use a bit triggered real time trend to plot a point every 100ms. Right now I have a cyclic interrupt, for the trend trigger, with a cycle time of 10ms but I am getting points every 125ms on the trend. The triggers HMI tag's acquisition cycle is 100ms. 

If anybody knows how to better control these trends it would be very helpful. 

Thank you. 

Hi EE.Stin,

Welcome to the forum!

We need more information to answer your question.

• Please tell us the type and firmware version of your PLC and the version of STEP 7 you are using.
• What is the origin of the value you want to use for your trend? Is it from a hardware signal? If so, please tell us more about the hardware.
• Finally, what HMI software and device are you using?

Kind regards
Stefan

Stefan Arcularius

Hi EE.Stin,

Welcome to the forum!

We need more information to answer your question.

• Please tell us the type and firmware version of your PLC and the version of STEP 7 you are using.
• What is the origin of the value you want to use for your trend? Is it from a hardware signal? If so, please tell us more about the hardware.
• Finally, what HMI software and device are you using?

Kind regards
Stefan

 I am using a CPU 1214C DC/DC/Rly with firmware version v4.4 and step 7 basic v17.

The trend data comes from a AI that is normalized and scaled with a FC in the OB1. The hardware that the AI is coming from is  AI 4x16BIT_1, with an integration time of 60hz/16.6ms and a weak smoothing.

I am using a TP700 comfort with firmware v15.1 and WinCC comfort v17. with TIA portal v17

Hi EE.Stin,

I assume you mean the analog input SM 1231, 4AI 16bit (6ES7231-5ND32-0XB0). This module would be fast enough to provide a new value within 100ms, so the module itself would not be the cause of the effect you are seeing.

However, you should make sure that the PLC itself delivers a new value to the panel at least every 100ms. The easiest way to do this would be to use the trace functionality to sample the cyclic interrupt OB responsible for your value.

You should also be aware of using a peripheral access within the OB or assigning the input addresses to the OB to get the process image updated each time the OB is called.

Kind regards
Stefan

Thank you for the suggestions, I have not fixed it yet but I had to start working on some thing else so I will be returning to this later. however I will be trying the peripheral access. 

I also have already tried the bit triggered buffer option and it works well, however the amount of working memory used for the arrays was too high for the project and I had to consider another option.