LabVIEW device simulators - Bronkhorst FLOWBUS

Introduction

LabVIEW program development benefits greatly from the availabilty of the required device drivers. Another tool in program development would be to have either the real devices or some means to emulate those devices.

For programs, that include Bronkhorst mass flow controllers, Bronkhorst provides a simulator for their mass flow controllers as part of their FlowDDE tool. However, if you don't want to use FlowDDE, for example because you don't want to add an additional software layer, there is no Bronkhorst device simulator. The provided LabVIEW tool provides a solution as it emulates devices using the FlowBus protocol. It will not emulate all possible functions but it does emulate the two basic functions, 'write setpoint' and 'read process value'. FlowDDE could still be used to check the configuration of your mass flow controllers.

Usage principle

The simulator can be used on the same computer on which you develop your LabVIEW application or on a separate simulation computer. In either case a real physical serial connection must be made. This also ensures the serial port can be tested even before the actual devices are present.

Changing a setpoint on your application will be received by the simulator which will change the corresponding simulated process value by moving it toward the setpoint. This resembles a real system which is enhanced by adding some noise to the process value.

The directory which contains the simulator also contains an ini file. This file describes which comport must be used and which devices must be simulated. Flow ranges don't have to be provided because the FlowBus protocol uses 32000 as the full scale value for any device.

If the ini file doesn't exist, then running the simulator will create it with default values. For the comport this will be COM1 and for the device addresses this will be 3 and 4. Usually 3 and 4 are the node addresses for channel 1 and 2 in FlowDDE.

The ini file looks like this:

[device settings]
mass flow controllers modules = "3,4"
com port = "COM1"

User interface

On the user interface there are 3 main sections

Download

simulator bronkhorst.zip

Remarks

• All VIs have been made with LabVIEW 2012 SP1 Professional Development System.
• The main vi, library and ini file should all be in the same directory.
• While using the simulator the cable for serial communication should be a NULL modem cable.
• FlowDDE can not be used at the same time as the Bronkhorst simulator.

Bart Boshuizen, 2013/10/23