iSMA-B-AAC20 Hardware User Manual
www.ismacontrolli.com
DMP239en | 1st Issue rev. 0 | 02/2022
page 13 of 42
4.6.2 RS485 COM2
Figure 15. RS485 connection
4.6.3 1-Wire
1-Wire is a special protocol for device which is made by the Dallas company. Temperature
sensors use DS18D20 chip. The 1-Wire bus uses 3 wire cable (+5 VCC, Data, GND) of
maximum 100 m long (it is recommended to use shorter distance) and up to 32 sensors.
All iSMA-B-AAC20 devices are equipped with a 1-Wire port which uses two analog
outputs, AO5 and AO6.
Figure 16. 1-Wire connection
4.6.4 M-Bus
The M-Bus (Meter Bus) was developed to fill the need for a system for the networking and
remote reading of utility meters, for example, to measure the consumption of gas or
water in the house.
M-Bus devices can be connected directly only to the iSMA-B-AAC20-M
WARNING!
Before connecting a 1-Wire device to the controller, please add a 1-Wire
network first. It will block the possibility of increasing voltage above 5 V and protect
the 1-Wire sensor against damage.
