Bronkhorst LIQUI-FLOW mini (till 01-07-2013) - Manual (Page 12)

9.17.065 page 12
3 Basic operation
3.1 General
A LIQUI-FLOW mini instrument must be powered with +15…24 Vdc. The instrument can be operated by means of:
•
Analog interface (0…5 Vdc; 0…10 Vdc; 0…20 mA or 4…20 mA)
• Digital RS232 interface (connected to a COM-port on 38400 Baud)
Switching between digital operation (in RS232 mode) and analog operation is done by setting the parameter IOStatus.
See section 4.1.5 for more details.
3.2 Analog operation
At analog operation following signals are available:
•
measured value (analog output)
• setpoint (analog input, not used)
• valve voltage (not used)
The type of installed analog interface (0…5 Vdc; 0…10 Vdc; 0…20 mA or 4…20 mA) can be found in the model key of
the instrument. Refer to paragraph 2.15.
When operating the instrument through the analog interface it is possible to connect the instrument
simultaneously to RS232 for reading/changing parameters (e.g. settings or fluid selection).
3.3 Manual interface: micro-switch and LED’s
By means of manual operation of the micro push-button switch some important actions for the instrument can be
selected/started. These options are available in both analog and digital operation mode.
These functions are:
- reset (instrument firmware-program reset)
- auto-zeroing
- restore factory settings (in case of accidently changing of the settings)
The LED’s on top of the instrument can also be used for manual operation of some options. The green LED will indicate
in what mode the instrument is active. The red LED will indicate error/warning situations.
For details see “manual interface” in Operation Instructions Digital Instruments (document nr.
9.17.023, Chapter 10)
3.4 Basic RS232 FLOW-BUS operation
Digital operation adds a lot of extra features (compared to analog operation) to the instruments.
Such as:
- Up to eight selectable fluids (calibration settings for high accuracy)
- direct reading at readout/control module or host computer
- testing and self diagnosis
- identification (serialnumber, modelnumber, device type, user tag)
- adjustable minimal and maximal alarm limits
- (batch) counter
RS232 FLOW-BUS 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.