How many M-Bus devices can I connect to one single PCD?

FAQ #101364

 

... but by increasing the number of devices you will sooner or later reach one of these limits:

• up to 250 devices can be addressed (with primary addressing)
• the signal converter supplies power for a limited number of devices (PW6=6, PW20=20, an so on)
• the number of PCD register is limited. Each M-Bus device will need about 20..30 registers.
• the Program memory of the PCD is also limited. Each M-Bus device will use about 400..800 lines of code. Add about 5000 lines for the driver itself (each driver).
• the total reading cycle of all devices will be affected by the number of devices.
  Depending on the type and the speed, you may need up to 1 minute for 10..20 devices already.
• we also noticed that large M-Bus networks are more often affected by cabling errors and disturbances. 
  

Therefore, we recommend, to limit the number of devices to 30..50 per network.

The 2 last points can be solved by using more than one serial line, converter and M-Bus driver.