# How many sensors do we need to monitor three factories?

Usually one for each network segment you want to watch at each site, which typically means one to three per plant. The number depends on where traffic can be copied: a SPAN port on a plant's core switch often sees the traffic between office and production and between the SCADA servers and the line switches, while traffic inside a machine's own switch needs a sensor or TAP closer to it. Start with the boundary between office and production at each plant, then add the segments where controllers are programmed. Every plant needs a small host to run the sensor and a way to send alerts out. With NetSenX, each agent on a SPAN or TAP port counts as one device for the whole segment it watches, all plants appear in one dashboard, and the OT protocols are read from the Pro plan. The pricing page shows how many devices each plan includes.

FAQ: [OT and IoT](https://netsenx.com/en/faq/ot) · https://netsenx.com/en/faq/how-many-sensors-do-we-need-for-several-plants

## Read next

- https://netsenx.com/en/ot-network-monitoring
- https://netsenx.com/en/pricing

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