VorTek U44 Series, Instruction Manual

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Series U44 Instruction Manual
M-000-00090
38
6. Appendix 1 – Serial Interface Network
Use and Communications Protocol
6.1 Overview
The flow meter is provided with a UART protocol and can also be operated by using RS-485 Modbus.
The two structures that can be used for networking are applying the analog current output method or directly
applying the UART communication method of the flow meter. The first option is applicable for replacing an
old meter in the previous monitoring network. The second option is used for a new monitoring network.
When the serial port communications method is directly used to implement a monitoring network system, the
address identification code of the flow meter is used as a network address code. Expanded command set with
[W] is used as communication protocol.
6.2 Connection via RS-485 to the Host Device
6.3 Modbus Communications Protocol and Use
6.3.1 HL Protocol
This flow meter is equipped with HL communication protocol. The host device will request the flow meter
to respond after sending a “command”. Asynchronous communication baud rate is 9600 BPS in general.
Single byte data format (10 bits): One start bit, one stop bit, and eight data bits. One data character string is
used to indicate the basic command, while one ENTER is used to indicate the end of the command.
Common Communication Commands:
Command Description Data format
RFR(cr)(lf) Return to Transient Flow ±d.ddddddE±dd(cr) Note 1
RVV(cr)(lf) Return to Transient Velocity ±d.ddddddE±dd(cr)
RT+(cr)(lf) Return to POS Total ±ddddddd.dE±d(cr) Note 2
RT-(cr)(lf) Return to NEG Total ±ddddddd.d±d(cr)
RTN(cr)(lf) Return to NET Total ±ddddddd.d±d(cr)
RTH(cr)(lf) Return to Total (Heat Quantity) ±ddddddd.d±d(cr)