LabVIEW
Bronkhorst ProPar Issue
Good day all,
Currently working on a very basic setup using a Bronkhorst Flexi-Flow sensor. The point of this Flexi-Flow is actually to run on FlowBus communication in order to daisychain more Flexi-Flows later on and visualize the measured data through LabVIEW using the FLOWBUS library. The issue here is that Flexi-Flow paired with FlowBus communication is relatively "new" and considering the Flexi-Flow measures Inlet Pressure, Flow, Outlet Pressure, and more, while the LabVIEW FLOWBUS library only has a limited amount of functions (excluding a way to choose low level parameters to measure, from what I could tell) makes it quite difficult to fully control/measure the Flexi-Flow in LabVIEW. Because of this, I've decided to use the ProPar library in LabVIEW which allows low level parameter indexing while still allowing control and monitoring of Bronkhorst devices.
In short, I'm using ProPar communication to monitor and control a Flexi-Flow through LabVIEW. When wired correctly and if I follow the Flexi-Flow data sheet, I can control and monitor all necessary parameters except Inlet Pressure and Outlet Pressure. It does measure something but it's apparently static (I did put some external influence on all inlets and outlets with no change in value or results) and does not reflect the internal pressure according to the FlowSuite 2 software (Bronkhorst software where you can control and monitor your Bronkhorst components).
Note: In order to measure Inlet/Outlet Pressure from the Flexi-Flow through LabVIEW, a low level read parameter function is implemented which uses process and parameter numbers (provided by the Flexi-Flow manual) to determine which parameter it is reading/measuring. There are different low level read functions and I've tried them all - I've currently left it on Read Long Parameter. Each low level read parameter function I implemented
provides different results but none reflect the actual pressure behavior according to the FlowSuite 2 measurements.
I've uploaded my project and shared a PDF of the data sheet. Any advice on what I'm doing wrong here or how I can accurately measure the inlet/outlet pressures would be great.
Kind regards,
PDB
The Bronkhorst ProPar protocol is not that complicated but the naming conventions can be a bit confusing. The ProPar protocol itself can be in ASCII or in binary. The LabVIEW library from Bronkhorst only implements the ASCII variant. This only allows to communicate with a Bronkhorst device through its RS-232 device, which is usually located on the non-standard DB-9 connector. This is not an RS-232 connector, it simply contains various digital and analog signals and two of them are the serial Rx and Tx data lines. These do conform to RS-232 electrical level, so with an according custom cable can be connected to a normal RS-232 interface connector, but never connect a normal RS-232 connector to this Bronkhorst connector with a normal RS-232 cable. That has the potential to destroy the Bronkhorst electronics or your RS-232 interface or both.
The Bronkhorst devices themselves can then communicate through a specific Fieldbus interface with each other. This can be the Bronkhorst Flowbus interface or another Fieldbus interface like Profibus, EtherCAT or sometimes also Modbus TCP. The Flowbus communication between the devices is using the binary ProPar protocol through an RS-485 electrical bus interface. This is necessary since all the devices are connected in parallel on this bus.
Your FlexiFlow device is a newer series that is a bit different. It has normally a Modbus RTU/Flowbus RS-485 interface and power supply input on the DB-9 connector on its upper side and a USB-C interface on the side. A second variant also has two Ethernet connectors to support Ethernet/IP, EtherCAT, Profinet or Modbus TCP. I haven't had a chance to play with FlexiFlow devices yet but suppose that you connect your device through the USB-C interface to your PC and that it represents itself as a virtual serial port in the PC.
As to accessing ProPar registers not implemented by the Bronkhorst VI library: If you look into the various VIs in that library you will find that they all call into the same low level VI that packs device id, register type, register number, data type and any parameters into a ProPar message to send and returns status and decoded data according to the data type when appropriate. Here you can find the documentation of the ProPar protocol and at the end a list of Flowbus register addresses, their data type and meaning. Please note that it contains many more registers than what your VI library implements access for. Not all of these registers apply to every Bronkhorst device, since Bronkhorst produces several types of devices such as various types of flow controllers, but also flow meters, pressure controllers and meters and controlled evaporator and mixer devices which all can be usually controlled through a Flowbus connection.
With this information it is relatively simple to implement your own extra VIs that call the same low level Bronkhorst VI to access registers that the standard library doesn't implement. If you can't find a specific register number in this list that you know should exist, this could be because above document is already a bit older and may not have been updated with possible new features of the relatively young FlexiFlow devices. In that case simply contact Bronkhorst technical support with the specific details. They are usually very helpful and respond almost always within one or two days.
