Ensayos

Chem. Eng. Comm., 192: 137–144, 2005 Copyright # Taylor & Francis Inc. ISSN: 0098-6445 print=1563-5201 online DOI: 10.1080=00986440590473290

Data Acquisition and Control of a 22 L B. Braun Fermenter Using LabVIEW
HANJING HUANG TINGYUE GU
Department of Chemical Engineering, Ohio University, Athens, Ohio

MURRAY MOO-YOUNG
Department of Chemical Engineering, University of Waterloo, Waterloo,Ontario, Canada
The flexible and automatic monitoring and control of a 22 L B. Braun Biostat C fermenter using LabVIEW software were achieved by establishing a serial interface between the fermenter’s control unit and a personal computer. This setup was also used for the on-line monitoring of the DO change in a custom-made 50 L airlift bioreactor. Keywords: Bioreactor control; Data acquisition;LabVIEW; Airlift bioreactor

Introduction
Fermentation is a very complicated process, and feedback control of fermentation is a useful strategy to guarantee a successful run. LabVIEW software is a powerful software program for data acquisition and control with increasing popularity. It supports IEEE488 (GPIB), RS232=422, and VXI, as well as plug-in A=D, D=A, and digital I=O boards (Jamal,1994). This work utilized LabVIEW to achieve flexible monitoring and control of a 22 L (15 L working volume) B. Braun Biostat C fermenter (B. Braun Biotech International, GmbH, Melsungen, Germany).

Experimental Setup
LabVIEW Software and Personal Computer The graphical programming environment LabVIEW (LabVIEW for Windows, Version 4.1, National Instruments, Austin, Tex.) ran on a Pentium personalcomputer with Microsoft Windows 95 operating system. User-written LabVIEW
Received 6 September 2002; in final form 26 June 2003. Address correspondence to Tingyue Gu, Department of Chemical Engineering, Ohio University, Athens, OH 45701. E-mail: gu@ohio.edu

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programs are called ‘‘virtual instruments’’ (VIs). VIs have three main parts: the front panel, blockdiagram, and icon=connector. The front panel provides the user an interface for data inputs and outputs. The user operates the front panel by using the computer’s keyboard and mouse. Behind the front panel is the block diagram that is responsible for the actual data flow between the inputs and outputs. The icon=connector defines data flow between subroutines (Wells, 1994). The LabVIEW programs in thiswork can also be used in newer versions (such as Version 6) of the LabVIEW software. Fermenter Settings In the 22 L B. Braun Biostat C fermenter, pH, stirring speed, temperature, and airflow rate are controlled by a DFC-2 hardware process control unit equipped with on-off and Proportion integral derivative (PID) controllers. The pO2 is measured by a steam sterilizable electrode. Agitation andairflow rates are controlled by internal PID boards, according to the set point values addressed by the pO2 controller. Without additional software and hardware, flexible scheduling of fermentation events and automatic data acquisition cannot be achieved. LabVIEW is an ideal tool in this case to improve the situation. The fermenter’s control unit has to be set up for a computer connection. To do this,the user goes to the MAINTENANCE menu on the control unit’s display and steps down to the HOST setup, and then sets the following parameters: ADR ¼ 1, SPEED ¼ 9600 bd, DATA ¼ 7 bit, STOP ¼ 1 bit, PARTY ¼ EVEN. Communication Port Setting The connection between the fermenter and the computer was established through a non-powered RS-232 to RS-422 signal converter (Model 263F, Telebyte, Inc.,Greenlawn, N.Y.) connected to the computer’s serial port 2 (RS-232 port 2). No additional power supply was needed for the converter due to the short distance between the fermenter and the computer. Serial port 1 was used for the mouse. The RS-422 interface is not as sensitive to interfering signals as the common RS-232 interface. The RS-232 to RS-422 signal converter is equipped with a ninepin...