Hey

I have a few questions regarding ModBus? How many typical Modbus nodes are hooked up to a master slave? I know it can hold up to 127 or 227 slaves, but what does an average protocol usually hold? Also you guys stated that there is 7.2 million nodes hooked up world wide. That number seems very low? Is there a reason its that low?

 

Hi,

The normal RS485 will support up to 32 nodes/network. I think Schneider recommends 8-10 slaves/Modbus network.

The more nodes on the network, the higher update time. and if you have a non time-critical application you can connect 31 slaves to your master. However, if you a more time critical application you will have to do some calculations as to how many slaves that can be connected.

my 2 cents

/Patrick L

 

It is pretty much impossible to accurately estimate the number of Modbus nodes in this world since - unlike an ODVA or Profibus or IEEE Ethernet devices - there is no central registry of serial numbers or 'MAC' codes.

Many 'Modbus-enhanced' devices may not even be used with Modbus - my company alone (Digi) probably has well over a million 'Modbus-enhanced' devices out in the world, meaning they understand Modbus protocols, timing, bridging, queueing and so on. But we have no way to know how many users enable that, or even what they do with our products.

That's one of Modbus's charms - free is beautify.