Inovance MD500T75G - Page 263

MD500 User Manual 9. Peripheral and Options
- 263 -
Ƶ
RS485 Bus Topology
7KH56EXVWRSRORJ\LVVKRZQLQWKHIROORZLQJÀJXUH
*
Master 1
485+
485-
Matching
terminal
resistor
* It is controlled by the
MXPSHU-3.
*
Node 2
CGND
Node 3
485+
485-
Shield
485+ 485+485- 485-CGND CGND
* It is controlled by the
MXPSHU-3.
Matching
terminal
resistor
It is recommended to use an STP cable as the RS485 bus and use a twisted cable to connect 485+ and 485-. Connect a matching
WHUPLQDOUHVLVWRURIȎUHVSHFWLYHO\DWERWKHQGVRIWKHEXVWRSUHYHQWVLJQDOUHÁHFWLRQ7KH56EXVDOORZVFRQQHFWLRQRID
maximum of 128 nodes and the distance of each node branch must be smaller than 3 m. Connect the reference ground of all nodes
together.
The connecting modes of multiple nodes are described as below:
1. Daisy chain connection mode (recommended)
Node
1
Node
2
Node
3
Node
4
Node
N
RS485 bus
Recommended
2. Branching connection mode (common)
The distance from the bus to the node cannot exceed 3 m.
Master
1
Node
2
Node
3
Node
4
Node
N
RS485 bus
3 m
3 m
3m
Common
3. Star connection mode (prohibited)
Master
1
Node
2
Node
4
Node
7
Node
5
Node
6
Node
3
Prohibited
efesotomasyon.com