Connecting To The Host's Rs-422A/485 Port - Omron NT31 Setup Manual

Connecting to the Host's RS-422A/485 Port

Reference:
5-2

Connecting to the Host's RS-422A/485 Port

98
S The internal circuit of the NT31/NT31C is shown below.
+ 10 (RDB)
−
16 (RDA)
Terminal resistor (120 Ω)
S For details on setting the terminal resistance of NT-AL001-E, refer to Settings
at the RS-232C/RS-422A Convertor Unit (NT-AL001-E) (page 86).
The methods for connecting the RS-422A/485 port of the NT31/NT31C and the
RS-422A/485 port of the host are described here. There are the following meth-
ods.
The following discussion is focused on the connection method to OMRON PLCs
(By using the memory link method, a connection can be made to any arbitrary
RS-422 unit). When making a connection to a host other than OMRON PLCs,
refer to the PLC Connection Manual (V042-E1-j) or Multi Vendor Connection
Manual (V060-E1-j).
• Method in which the RS-422A ports of the NT31/NT31C and host are con-
nected directly by an RS-422A cable (page 115).
When this method is used, the cable length can be extended up to 500 m.
PT
• Method in which the RS-485 ports of the NT31/NT31C and host are connected
by an RS-485 cable (page 119).
When this method is used, the cable length can be extended up to 500 m.
This connection method can be used only with the NT link (1:N) method
(standard or high-speed) of type RS-485.
PT
• Method in which the RS-422A ports of multiple NT31/NT31Cs and the
RS-422A port of the host are connected in a 1:N connection (page 120).
This connection method is used with the RS-422A type NT link (1:N) method
(standard or high-speed).
PT
• Method in which the RS-485 ports of multiple NT31/NT31Cs and the RS-485
port of the host are connected in a 1:N connection (page 123).
Making a connection here inserts a terminator between
+ (RDB) and − (RDA).
9 (TRM)
RS-422A cable
(max. 500 m)
RS-485 cable
(max. 500 m)
RS-422A cable
(max. total length 500 m)
Section 5-2
Host
Host
Host