Rs485 - TagMaster XT-1 Installation Manual

XT-1 Installation Manual

RS485

The RS485 interface is used for host communication and supports ASCII output and TAGP. It generally
supports longer transmission distances than RS232. Detailed settings are configured in firmware, see
§4.2.3.3.3. The interface has 1500 VDC isolation and overvoltage protection.
Figure 15 RS485 connection, overview and detail
The hardware supports 2-wire (DIP S301:1-2 ON) and 4-wire communication, half duplex and full duplex as
well as multi-drop. When using RS485 communication, correct termination of the interface should be
considered in order to handle transmission-line effects. The XT-1 has a built-in option (DIP S301:3 ON) of
120 Ω termination on the receive side (to be used at each end of the RS485 chain), and an option
(DIP S301:4-5 ON) of 620 Ω bias on the receive side (to be used at one node in the RS485 chain). The
options using DIP switches are detailed in Figure 16 and also described in §3.11.
S301:1 S301:2
Figure 16 RS485 DIP switch configuration
5V iso
620 Ω
S301:4
RX+
120 Ω
S301:3
RX-
RS485
driver
620 Ω
S301:5
TX+
TX-
13-111 02, 2014-RO-012, 2014-04-30
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