iSMA-B-MAC36NL User Manual
Version 1.4
www.gc5.pl
Page 14 / 51
When the switch is in the BIA position it connects the biasing resistors 680
Ω (pull
-down to
ground SG and pull-up to +5VDC) to the RS485 bus. The biasing is added to the RS485 bus
in order to reduce communication failures.
WARNING! Only one single device on the network can have biasing resistors connected.
Connecting biasing resistors on two or more devices on the one single RS485 bus will take
the opposite effect
–
increase the number of communication problems.
Figure 9. RS485 network biasing
2.3.3
M-Bus Connection
M-Bus devices can be connected directly only to the iSMA-B-MAC36NL-M, hardware version
with M-Bus interface (max. 20 devices).
Figure 10. M-Bus connection