112
Connecting to the Host’s RS-232C Port
Section 5-1
5-1-5
Setting the Terminal Resistance for RS–422A/485 Communica-
tions
The serial port B connector of the NT31/NT31C has a terminal resistance setting
terminal (TRM).
In RS-422A/485 communications, a terminal resistor must be set at the device at
the end of the communication cable, but not at any other device.
The NT31/NT31C has a built-in terminal resistor, and whether or not the terminal
resistance is applied is set by the wiring at the terminal resistance setting terminals
(pins No. 9 and 10 of serial port B). The terminal resistance is 120
Ω
. When carry-
ing out RS-422A/485 communications using serial port B, short between terminals
No. 9 and 10 at the NT31/NT31C at the end of the RS-422A/485 cable. Leave
terminals No. 9 and 10 open at NT31/NT31C units other than the one at the end of
the cable.
When not using RS-422A/485 communications, the terminal resistance setting is
ineffective.
In order to set the terminal resistance, wiring work is required at the cable’s con-
nector: carry out the wiring correctly by referring to APPENDIX E “Making the
Cable”, page 661.
Abbreviation
FG
-
-
TRM
RDB (+)
SDB (+)
-
-
-
Pin number
Connector
hood
-
9
10
11
12
-
25
Terminal resistor setting
Pin Nos. 9 and 10
Function
Shorted
Terminal resistance is applied.
Short only at the NT31/NT31C connected to the end of an
RS-422A/485 cable.
Open
Terminal resistance is not applied.
Leave the terminals open when connecting an NT31/NT31C
anywhere other than at the end of the RS-422A/485 cable.
Note
Before connecting or disconnecting cables between devices, make sure that the
power supply to all of the connected devices (NT31/NT31C, PC, etc.) is OFF.
Reference
- The internal circuit of the NT31/NT31C is shown below.
16 (RDA)
9 (TRM)
10 (RDB)
+
−
Terminal resistor (120
Ω
)
Making a connection here inserts a terminator between
+ (RDB) and
−
(RDA).
- For details on setting the terminal resistance of NT–AL001, refer to “Settings at
the RS-232C/RS-422A Convertor Unit (NT-AL001)” (page 98).
Содержание NT31 Series
Страница 1: ...Cat No V043 E1 2 Programmable Terminal NT31 31C OPERATION MANUAL...
Страница 2: ...iii NT31 31C Programmable Terminal Operation Manual Produced March 1999...
Страница 41: ...30 Before Operating Section 1 5...
Страница 75: ...64 Using a Memory Unit NT31 NT31C without V1 Section 3 6...
Страница 160: ...149...
Страница 174: ...163...
Страница 193: ...182...
Страница 211: ...200...
Страница 235: ...224 c Return to the screen on which screens are specified...
Страница 262: ...251...
Страница 284: ...273 The printer type control protocol and printing method are set with the memory switches of the NT31 NT31C...
Страница 347: ...336 Screen number 5 is set for touch switch 1 To next screen When touch switch 1 is pressed Screen number 5...
Страница 360: ...349 It is not possible to control a gloval window by touch switch operation...
Страница 375: ...364 For details on the method of display depending on the General settings refer to Common Attributes page 358...
Страница 391: ...380 1 The 100 value 0 value and 100 value must comply with the following relationship 100 value 0 value 100 value...
Страница 468: ...457 254 255 0 2 7 1 4 5 3 3 0 0 0 5 9 8 0 3...
Страница 476: ...465 Special Functions Section 7 16...
Страница 495: ...484 OFF...
Страница 610: ...599 Commands Responses Section 9 3...
Страница 630: ...619 Examples of Actual Applications of Memory Link Section 10 2...