Networked Instrument Communication
TCP/IP is a widely used, standard networking protocol that enables devices to exchange information. The key to TCP/IP is the
breaking of information into "packets" that are structured to allow error detection and correction (by using redundancy mechanisms
such as checksums). This technique guarantees error-free data transport and represents an excellent basis for the implementation
of the "device checks" and "system checks" mandated by 21 CFR Part 11. Communication in a TCP/IP environment is, by definition,
highly dynamic. Addition or removal of idle devices in the network does not affect ongoing communication between the other
devices. Figure 1 illustrates a typical configuration of networked instruments in a distributed, client/server environment.
Requirements for the qualification of computer network infrastructure are discussed in the "Qualifying Network Infrastructure"
article in this series.
Electronic records generated by an instrument are only reliable and trustworthy if the communication between instrument and
the system controller is reliable and trustworthy. Level-4 instrument control uses advanced mechanisms for automatic tracking
of instrument identification and configuration, and it is a prerequisite for the implementation of additional failure warning
mechanisms such as EMF. Level-4 instrument control is a relevant and important measure to obtain trustworthy and reliable
electronic raw data, metadata, and results that must be kept according to predicate rules such as GLP or cGMP and which are
consequently subject to 21 CFR Part 11. Level-4 mechanisms implement operational system checks and device checks that are
required according to Part 11 and reinforced by the Part 11 guidance released in August 2003.
Figure1: Typical topology for a networked data system
1.Assess the level of control of instrumentation used in the laboratory.
2. Assess whether the data generated by the instrument is subject to a predicate rule.
3. Assess the risk of non-compliance for this instrument and document your risk assessment.
4.If instrument communication uses proprietary interfaces, check for adherence to your internal IT support guidelines.
5. For instrumentation not directly controlled by the data system (level 1), plan the procedures necessary to document instrument
6.For instrumentation claimed to be controlled, determine whether the instrument manufacturer officially supports the implementation.
Some data system suppliers only implement instrument drivers under a mutual disclosure and support agreement with the original
7. If the instrument manufacturer does not officially support the implementation of the control software, plan additional
qualification and acceptance tests to obtain a high degree of assurance that control and communication are accurate and reliable.
8. Adapt internal procedures to take advantage of the additional diagnostics and maintenance, identification, and configuration
information available in level-4 systems. Electronic records generated by an instrument are only reliable and trustworthy
if the communication between instrument and the system controller is reliable and trustworthy. Level 4 instrument control
is an adequate mechanism to ensure this.
9. Define test cases for boundary conditions. For example:
- Does the system reliably synchronize all devices required for an analysis?
- Could a device’s failure to start go unnoticed due to a contact closure problem?
- If the instrument has a local user interface, is it “locked” while data are being acquired by the computer? Alternatively,
does it track parameter changes performed at the local interface while data are being acquired by the computer?
- Does the system quickly detect power failures of a connected device or are data lost until a time-out situation occurs?
1. FDA. Code of Federal Regulations, Title 21, Part 11; electronic records; electronic signatures; final rule. Federal Register 1997; 62(54):
2. FDA. Guidance for industry: Part 11, electronic records; electronic signatures — scope and application. (draft February
2003, final version August 2003). Available at URL: www.fda.gov/cder/guidance/5667fnl.pdf.
3. Huber L, Winter W. Implementing 21 CFR Part 11 — electronic signatures and records in analytical laboratories, part 5 —
the importance of instrument control and data acquisition. BioPharm 2000; 13(9).
4. Agilent Technologies. Generic instrument control. Cerity Networked Data System for Pharmaceutical QA/QC Handbook. Palo Alto (CA): Agilent; 2003.
5. Dickinson I, Eichberger H, Messaros D, Walter HD, inventors; Hewlett-Packard, assignee. User interface for a remote diagnostic
device. US Patent 5588109. 1996 Dec 24.
6. Giuffre B, Winter W. New Part 11 guidance,network monitoring, network qualification. Proceedings of Agilent Technologies
E-Seminar; 2003 Oct. Available at