RS485-BL node multiple sensors per node

[Juan]

Hi im using multiple dragino products and i have a question about the RS485-BL Lorawan node, the question is simple and sorry if is something obvious.

I have various RS485-BL nodes with one sensor each working perfectly; can i connect multiple sensor of same type to just one node? (as fas as i know is possible) if yes it can be done directly? (so 2 same sensors cables conected directly to the node A-B conections in the node) or need extra hardware to control that (like a hub or something)? in that case witch hardware is necesary/recomended?

Many thanks in advance.

[Adrian M]

Hi, Juan!

As far as I know, you can connect multiple RS485 devices on the same bus, as long as each device is only responding at messages addressed to it (or it should be, in a MODBUS topology). As I know, there should also be a broadcast address (245, or 250-decimal, if I remember right), at which every sensor is waking up and listening. Otherwise, a device respond only if the address field contains its own address. If not, is going to sleep again.

However, you should ensure that your RS485 devices are addressable (it is not mandatory). If they are, then you don't need any additional hardware, just simply connect them on signals A and B. It should be no problem for a number of 10-15 devices coupled together on the bus and having different addresses. So, you should connect them one at a time and setting its individual address, different from one device to the other. After that it should be ok to connect them together.

Hope this helps!

Adrian