Data from Modbus server input register value switching between 0 and true value

I have looked at Snap7 a few times, I think it was this that inspired me to buy a Raspberry Pi as I was going to have a go at building an html mini scada but I am self-taught at any type of programming, I feel I am lacking in some fundamental principles. I'm okay with Step7/WInCC/Startdrive after 5 years at work on a daily basis but text based languages are still quite alien to me. I often consider paying for some tuition. I spend most of my spare time playing/learning microcontrollers, I would definitely benefit from some skills in Python and Java. Arduino is the only exposure to C++ that I have had. Less than 3 years.

I am interested in your earlier suggestion about filtering out the 0 as a work around, for £60 I can add a DM8 12/24 to complete my hydroponic project without the Arduino I/O.

Matt

Hi ixo65,

I haven't had any joy with a connection between Node-RED and S7-1200 yet, not really spent much time on it. I am using both as ModBus clients, Node-RED is just dashboard trends and guages currently. 

It's an exciting arena that is not at all cost prohibitive, it's good to see all these technologies making it on this forum.

I really like the IOT 2020 and was excited about it when it appeared. I do find it really interesting and plan to buy one soon. I'm trying to clear unfinished projects. 

Matt

Matt zen Earthling

I am interested in your earlier suggestion about filtering out the 0 as a work around, for £60 I can add a DM8 12/24 to complete my hydroponic project without the Arduino I/O.

Matt

The easiest way for this is a threshold trigger and an arithmetic block, see attached example. Maybe you want expand it with additional conditions like checking for lost connection, if possible. For this you must define the states for it, e.g. the zero is present for a longer time.

The AI1 in the example is just for simulation.

Regards, Scorp

Thank you Scorp, this looks great!

I am currently installing this LOGO! and want to have some water pumping around by the end of the day. The weather it atrocious, so the temperature in the polytunnel is bearable a comfortable 18 degC. It was approaching 50 degC in there midweek, over 30 degC in the evenings.

Enjoy your Sunday!

Matt

I enjoy every "sun day" with temperatures under 30°C, for me 25°C is enough.

If you use the example, then remember the permanent storage of the last temperature not equal to zero, independent of lost communication or sensor fault. Think about a way to bridge your settings with a button or switch.

Nice Sunday, Scorp

Today was a good day. Now all connected up and calibrated.

I'm going for beer, cheers Scorp, ixo65