Bronkhorst RS232 interface - Manual (Page 4)

BRONKHORST ®
Page 4 RS232 interface 9.17.027
1 GENERAL PRODUCT INFORMATION
1.1 I NTRODUCTION
This manual will explain how to communicate with a Bronkhorst
1)
instrument to your PC/PLC using RS232 serial communication. You
have to write software yourself using the information of this
document in order to be able to operate these instruments.
Bronkhorst also offers software to easily operate digital instruments
with your PC using Microsoft Windows. On the highest supported
communication level, you may use FlowDDE channels for Windows
application‐programs with this facility. You can use the program
FlowDDE for easy connection between Windows applications (e.g.
Excel, Visual Basic, LabVIEW, Delphi, Borland C) and digital
instruments. There are several examples available for LabVIEW, Visual
Basic and Excel environments.
On a lower communication level, you can also use the FLOWB32.DLL for reading/changing parameter values.
To read and write parameter values from or to FLOW‐BUS devices directly through the available interfaces there is a
special protocol for messages between these devices. This protocol has been specially developed for Bronkhorst
equipment so no third party equipment can be connected. It consists of a hierarchical setup for instruments / nodes
(max. 126) containing processes (max. 127) with parameters (FBnr) (max. 32) which values can be set to certain values
to enable settings/properties for the instruments.
When operating a FLOW‐BUS system with a HOST computer, you need to know this message protocol if you choose to
drive the interfaces directly. When you use a RS232/FLOW‐BUS interface (without the micro‐switch and 2 LED’s), you
first have to initialise the interface. This can be done by means of sending some ASCII‐strings to the interface through
RS232. See chapter “Initialising RS232/FLOW‐BUS interface” for more details.
When you communicate directly via RS232 on a Multibus instrument or when you use a new type of RS232/FLOW‐BUS
(baud rates up to 38K4 with switch and 2 LED’s) interface, no special initialisation is needed.
1)
Bronkhorst: This includes Bronkhorst High‐Tech B.V. , Bronkhorst Cori‐Tech B.V. and
M+W Instruments GmbH.
1.2 M
ULTIBUS TYPES
In 2000 Bronkhorst developed their first digital instruments according to the “multibus” principle. The basic pc‐board
on the instrument contained all of the general functions needed for measurement and control, including alarm,
totalizing and diagnostic functions. It had analog I/O‐signals and also an RS232 connection as a standard feature. In
addition to this there is the possibility of integrating an interface board with DeviceNet™, Profibus‐DP
®
, Modbus ,
FLOW‐BUS or EtherCAT protocol. The first generation (MBC‐I) was based on a 16 bit
Fujitsu controller. It was superseded in 2003 by the Multibus type 2 (MBC‐II). This
version was also based on the 16 bit Fujitsu controller but it had several
improvements to the MBC‐I. One of them is the current steering of the valve. It
reduced heat production and improved control characteristics. The latest version
Multibus controller type 3 (MBC3) is introduced in 2011. It is build around a 72MHz
32 bit NXP ARM controller. It has AD and DA controllers on board which makes it
possible to measure noise free and control valves without delays. The internal
control loop runs 6 times faster compared to the MBC‐II therefore control stability
has improved significantly. It also has several improved functions like reverse
voltage protection, inrush current limitation and overvoltage protection.
MBC3 instruments can be recognised by the “MBC3” placed on lower left side
of the instrument label (see example).