Using Rs-485 Interface; Wiring Selection; Terminal Resistor - Mitsubishi Electric MELSEC FX Series User Manual

FX communication
3.3

Using RS-485 Interface

3.3.1

Wiring Selection

The wiring of RS-485 can either be one-pair or two-pair. The wiring method is decided according
to application usage. Please select the wiring method from the table below.
No protocol
(Use RS instruction) *1
Dedicated protocol
(Use computer link)*1
Parallel link *4
N:N network
&...
Recommendation, '
Note:
*1 When this product is added to the system, please match the wiring to the existing method of
the system.
*2 When using an FX
the "echo" of the commands sent from the FX
*3 Please use the FX
Full-duplex combination cannot be achieved with other configurations.
*4 For wiring parallel link, see section 2.4.
3.3.2

Terminal Resistor

A terminal resistor must be used at both ends of the communication line as described in section
2.3.3 and 2.3.4.
1 ) In the case of two-pair wiring, connect the terminal resistor
Ω
(330 , 1/4W) between terminals SDA and SDB and between
ter minals RDA and R DB. U se the resistors offered as
accessories with the product.
2 ) In the case of one-pair wiring, connect the terminal resistor
Ω
(110 , 1/2W) between terminals RDA and RDB. Use the
resistors offered as accessories with the product.
Usage
Half-duplex communication
Full-duplex communication *3
It is necessary to set the message
wait time to 70 ms or less.
It is not necessary to set the
massage wait time to 70 ms or less.
Use the on-demand function
... ×...
OK, Cannot use
-485-BD with this wiring method, remember to take account of/or ignore
2N
programmable controller and FX
2N
One-pair wiring
&
*2
×
×
&
*2
×
&
'
programmable controller.
2N
-485-BD together.
2N
Orange Orange Brown
Wiring 3
Two-pair wiring
'
'
'
'
'
'
×
330 Ω
1/4 W
Brown Brown Brown
110 Ω
1/2 W
3-6