Mitsubishi Electric QJ71MB91 User Manual page 152

6
PRE-OPERATIONAL PROCEDURES AND SETTINGS
6
- 15 6.5 Connection to a Target Device
6.5.2 How to connect the RS-422/485 interface
(c) Terminating resistor
Terminating resistor setting (or connection) is required for the stations of both line
ends.
For the QJ71MB91 side, connect a terminating resistor (packed with the
QJ71MB91), referring to this section and according to the specifications of the
target device.
For the target device side, connect or set a terminating resistor according to the
instruction manual of the target device.
(Terminating resistor to be connected to the QJ71MB91)
• For RS-422 communications, connect a "330
• For RS-485 communications, connect a "110
* How to distinguish terminating resistors
330
Orange Orange
Figure 6.12 How to distinguish terminating resistors
(d) When data communications are not possible at all
If data cannot be exchanged with the target device at all, check the polarity of the
target device.
If the polarities of the QJ71MB91 and target device do not match, reverse the
polarity of each signal on either device side. This may enable the data
communications.
POINT
Devices connected to the QJ71MB91 RS-422/485 interface must be all RS-422 or
all RS-485.
110
Brown
1/4W" terminating resistor.
1/2W" terminating resistor.
Brown Brown Brown