17 February 2020
Dan Barrera, global product manager, Ideal Networks
LAN cable certifiers are the go-to method to test twisted pair cabling.
But what is the difference between a certifier and other types of testers? And which to choose?
Put simply, the first two elements of a LAN cabling system are the cable and the connectors. Third is their installation and this is what LAN cable certifiers test.
When to choose a certifier. Quality connectors and cable will perform as advertised when properly installed in laboratory environments. In the field it’s very different so your system has to be tested once installed.
Cabling standards are critical for engineers. The main standardisation bodies are ISO/IEC with the 11801 series standards and ANSI/TIA with the 568 series of standards. These define performance requirements for components, cable and cabling.
What is a cable qualifier? Unlike certifiers, cable qualification has no defined tests, performance or accuracy specifications in the standards organisations. Qualification is up to the manufacturer of the LAN qualifier to decide what to test, accuracy of the instrument and how to report results.
The problem is that the results from one brand of qualifier cannot be compared to another. Plus, without a definition for pass/fail limits, what does it mean when a qualifier “fails” a cable? For these reasons, no major cable or connector manufacturer will accept results from a qualifier.
Qualifier or certifier? It is not always easy to tell whether a tester is a qualifier or a certifier. However, a certifier must:
• Meet ISO/IEC 61935 and TIA 1152-A accuracy requirements, find faulty components, installation mistakes and help ensure materials are genuine.
• Have ETL Level III/IIIe for up to 500Mhz or Level V for up to 3000 MHz for verified accuracy
• Measure NEXT, ACR-N and DC Resistance, Return Loss, Insertion Loss and ACR-F
• Specify a frequency range of at least 500MHz
Where do cable verifiers come in? Different testing equipment is used to test the different layers of an Ethernet/IP network.
For Layer 1, the physical electrical/optical signalling and cabling components, a verifier is often used to check cable and terminations. They test electrical continuity for shorts, opens, crossed and split pairs. They are inexpensive and invaluable since more than 80 per cent of problems are due to cabling faults.
However, remember! Where a warranty is required, a cable certifier is necessary as it uses radio frequencies on the cabling to measure pass/fail to ISO and TIA standards.
Layer 2 testers check cabling and Ethernet switches by counting network data frame loss (data transmission test). Unlike a Layer 1 qualifier, a Layer 2 tester does not measure electrical parameters; it measures the successful transmission of data across a cable or a network.
Layer 3 testers are similar but check performance between different networks through routers and Layer 3 switches by counting packet loss of actual network data.
