What is the maximum number of devices that can be connected to a Zigbee network?

1 Zigbee network types

Zigbee networks can be classified into three types: star, tree, and mesh. In a star network, one coordinator device acts as the central hub and communicates with multiple end devices. In a tree network, one coordinator device connects to multiple router devices, which in turn connect to multiple end devices. In a mesh network, any device can act as a router and relay messages between other devices. The network type affects the maximum number of devices because each device type has a limit on how many connections it can support.

2 Zigbee device types

Zigbee devices can be categorized into three types: coordinator, router, and end device. A coordinator device is responsible for creating and managing the network, and assigning addresses to other devices. A router device can join an existing network, route messages between devices, and allow end devices to join the network. An end device can join an existing network, send and receive messages, but cannot route messages or allow other devices to join. The device type affects the maximum number of devices because each device type has a different address space and memory capacity.

3 Zigbee address space

Zigbee devices use two types of addresses: network address and MAC address. A network address is a 16-bit identifier that is assigned by the coordinator or router when a device joins the network. A MAC address is a 64-bit identifier that is unique to each device and is used for security and device discovery. The address space affects the maximum number of devices because each network address must be unique within the network, and each MAC address must be unique within the Zigbee universe.

4 Zigbee memory capacity

Zigbee devices have a limited amount of memory to store information about the network, such as routing tables, neighbor tables, and address tables. The memory capacity affects the maximum number of devices because each device must store enough information to communicate with other devices, and the more devices there are, the more information there is to store. The memory capacity varies depending on the device type, manufacturer, and firmware.

5 Zigbee network size estimation

To estimate the maximum number of devices that can be connected to a Zigbee network, you need to consider the network type, the device type, the address space, and the memory capacity. While there is no definitive formula for calculating the maximum number of devices, general guidelines and assumptions can help you get an approximate figure. For instance, a coordinator device can support up to 20 router devices and 20 end devices; a router device can support up to 20 router devices and 20 end devices; an end device can only communicate with one coordinator or router device; and a network address can be reused if a device leaves the network or changes its parent device. Additionally, a MAC address cannot be reused if a device leaves the network or changes its parent device, and each device requires at least 4 bytes of memory to store each network address and 8 bytes of memory to store each MAC address. Consequently, for a star network, the maximum number of devices is 21; for a tree network, it is 421; and for a mesh network, it is 65535. However, these are only rough estimates, as the actual number of devices that can be connected to a Zigbee network may vary depending on the specific configuration, features of the devices, and application requirements. Therefore, it is advisable to test your Zigbee network before deploying it in a real environment and to monitor its performance and stability regularly.

6 Here’s what else to consider

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