6. Measurement Device Setup and Connection
6-10
Wiring of RS-485-Connected Measurement Device
6.2.2.
EQ100 has four RS-485 communications ports for RS-485-connected measurement devices.
Up to 31 measurement devices can be connected to one port (31 x 4 ports= Total 124 devices).
Reference
- Maximum transmission distance is 500m for RS-485 communications.
- For an RS-485 communications port cable, a shielded twisted-pair cable of AWG24 to 14
(0.205 to 2.081 mm
2
) must be used.
- To prevent malfunction, a shielded wire must be connected to the ground or FG terminal.
- For a device that is connected to the circuit end opposite to this product, a terminal resister of
120
Ω
(1/2W) must be attached (or the built-in terminal resistor, if any, must be enabled).
- The RS-485 communications port terminal has the built-in terminal resistor. The RS-485
communications port cable must be attached so that this product should be on one end of the
terminal as shown below.
Precautions for
Correct Use
- The RS-485 cables must be wired through measurement devices in one loop. Branching
and/or star wiring is not available.
Maximum Transmission Distance of 500 m
Up to 31 devices
