UNIPOWER
UP-2210R/P Hardware installation and configuration manual
45
7.3
RS-485
RS-485 is a serial communication that can be used together with some meters. It is similar to the
common RS-232 but works with larger distances. Another advantage is that you can connect
multiple meters to the same RS-485 cable (multi drop). This is useful in large sub-stations where you
want to connect several meters to the same modem.
RS-485 communication can be direct from the computer (using a signal converter) to the meter via a
twisted pair cable, but over a distance of less than 1 km. It may also be necessary to terminate
(jumper) the contacts (A to B) on the UP-2210 with a 120 Ω resistor to improve the communication
conditions. In this case, the resistor is only connected in the last unit.
RS-485 MUX
Computer or
Modem
Figure 39