Bronkhorst EL-FLOW Base 2014 - Manual (Page 14)

BRONKHORST HIGH-TECH
3 Basic Operation
3.1 General
An EL-FLOW base instrument can be operated by means of:
• Analog interface (0...5Vdc/0...10Vdc/0...20mA/4...20mA)
• Digital RS232 Flowbus interface (connected to COM-port by means of special cable on 38400 Baud)
• Digital RS485 Modbus interface.
Operation via analog or digital interface can be performed at the same time. A special parameter called
“control mode” indicates to which setpoint the controller should respond.
3.2 Analog operation
At analog operation following signals are available:
• measured value (analog output)
• setpoint (analog input)
The type of installed analog interface (0-5V, 0-10V, 0-20mA or 4-20mA) can be found in the model key of
the instrument. Refer to paragraph 1.6.2.
Setpoints below 2% of the full scale will be interpreted as 0% setpoint.
When operating the instrument through the analog interface it is possible to connect the instrument
simultaneously to RS232 or Modbus/RS485 for reading/changing parameters (e.g. controller response
or other fluid selection).
3.3 Basic RS232 Flowbus operation
RS232 Flowbus communication can be used for operating your instrument using the Bronkhorst
FLowDDE server application.
Physical layer and communication protocol are detected automatically upon reception of messages.
These messages must be sent using the correct combination of physical layer and communication
protocol. After every power-up the communication detection mode is active.
Dynamic Data Exchange (DDE) provides the user a basic level of inter process communication between
Windows applications.
FlowDDE is a DDE server application. Together with a client-application, either self-made or with a
SCADA-program from 3rd-parties, it is possible to create an easy way of data exchange between the flow
controller and a Windows application.
For example, a cell in Microsoft Excel could be linked to the measured value of the flow controller and
when the measured value changes, it will be automatically updated in the Excel spreadsheet.
Page 14 EL-FLOW Base Series Mass Flow Controllers 9.17.061