# Node-red-contrib-netvar - negative "REAL" Type PLC values arrive in node-red as null

**URL:** <https://discourse.nodered.org/t/node-red-contrib-netvar-negative-real-type-plc-values-arrive-in-node-red-as-null/27176>\
**Category:** General\
**Created:** [24 May 2020 08:19 UTC](https://discourse.nodered.org/t/node-red-contrib-netvar-negative-real-type-plc-values-arrive-in-node-red-as-null/27176 "2020-05-24T08:19:46Z")\
**Posts on this page:** 1\
**Showing post:** 8

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**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [24 May 2020 11:52 UTC](https://discourse.nodered.org/t/node-red-contrib-netvar-negative-real-type-plc-values-arrive-in-node-red-as-null/27176/8 "2020-05-24T11:52:29Z")

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> [@yoba](#):
>
> I would be very interested if you can give me further details on your last statement. I don't know if this is the place to discuss about that or send PM?

Here is fine.

so, I have used all of the above mentioned protocols (for years) and in my experience, in node-red (and general IoT), MQTT is simply the best medium. OPCUA is a BEAST (read the spec if you have a spare year). Its complex and heavy. dont get me wrong, OPCUA is a tremendous and detailed specification but if you want to get a simple value from A to b and you have MQTT at your disposal - chose that. every time!.

As for modbus - the nodes avaiable for node-red work for the most - but a quick search of this forum will reveal how much people A struggle with it and B how it can crash node-red (not good!)

Are you familiar with MQTT?

If not - read [this](https://discourse.nodered.org/t/linking-2-or-more-instances-on-a-local-network/24879/3)

In fact, give it ago - it will take you 5 minutes.

Lastly...

> [@yoba](#):
>
> As I precised above, I'm quite new to IoT world

I would strongly urge you to watch this playlist: [Node-RED Essentials](https://www.youtube.com/playlist?list=PLyNBB9VCLmo1hyO-4fIZ08gqFcXBkHy-6). It is by the developers of node-red. They're nice & short and to the point. You will understand a whole lot more in less than an hour. A small investment for a lot of gain.

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_[View the full topic](https://discourse.nodered.org/t/node-red-contrib-netvar-negative-real-type-plc-values-arrive-in-node-red-as-null/27176)._