Yokogawa µR20000 - Manual (Page 16)

1-4
IM 04P01B01-17E
1.2 Communication Functions Using the RS-
422A/485 Communication Interface (/C3
Option)
The recorder can be equipped with an optional RS-422A/485 communication interface.
For details on how to use the RS-422A/485 communication interface, see chapter 3.
Functional Construction
The following figure shows the relationship between the communication function of
the recorder and the RS-422A/485 communication interface. Perform communication
according to the respective protocol.
* Protocol is a set of rules that two computers use to communicate via a communication line (or
network).
PC
Connect the recorder and the
PC using a serial cable.
Setting/Measurement Server
Dedicated protocol Protocol
Interface RS-422A/485
Modbus Slave
Modbus protocol
Communication functions of the recorder
Application
Setting/Measurement Server
The functions are the same as those of the Setting/Measurement server of the Ethernet
interface. See page 1-1.
• RS-422A/485 communication interface settings: Section 3.5
• Commands: Section 4.2
• RS-422A/485 dedicated commands: Section 4.8
• Data output format: Chapter 5
Modbus Slave
• The Modbus protocol can be used to read the measured/computed data on your PC
by reading the input registers of the recorder. The communication input data can be
written or read by writing/reading the hold register of the recorder.
• For details on the Modbus function codes that the recorder supports, see section 3.4.
• This function can be used only when communicating via the serial interface (option).
• For a description on the settings required in using this function, see section 3.5.
Data from slave device
Data to slave device
Modbus master device
Modbus slave device
Serial communication
Recorder