The Direct Attach Controversy
The hot “discussion” amongst the RCDD’s LinkedIn site through BICSI’s RCDD Group is whether or not there is a standard that is EIA/TIA compliant that allows a UTP Category cable terminated directly into an IP port on a camera. The answer is “yes” and “no.” The “direct attach” configuration is a modular plug-ended horizontal cable at the device end which is not recognized in TIA-568 standardized data and voice applications, but has been accepted by the building automation standard, TIA-862 and the proposed ANSI/BICSI-005 ESS draft documents.
The TIA-568 recognizes a four-connector channel which includes a patch panel and patch cord on the TR side and a workstation outlet and patch cord on the device side. The understood “device” was originally deemed for computers and telephones which were the only networked devices at the time of the standards’ origination. This scenario protects the horizontal cabling when plugging and unplugging phones and computers at that end. Therefore, it is known as a user interface, because the user can interchange computers and/or phones at the workstation.
However, as disparate applications and other IP devices were being attached to the data/voice network, some unique challenges were introduced for the TIA-568 channel model. Although the TIA-568 was originally written for any IP application, considerations of the unique locations of end devices, such as access control, security cameras and wireless access points created issues. There are many reasons that patch cords and outlets at the device end cannot be deployed. These include: security and protection of the connection (an exposed patch cord to a security camera is easy to disconnect); the feasibility of a patch cord in tight spaces; adhering to only placing plenum-rated products in air-handling spaces (plenum patch cords are specialty items as are workstation outlets) and aesthetics (sometimes it’s just plain ugly and doesn’t fit the décor).
The TIA-862 BAS standard recognizes this and allows the elimination of an equipment cord in a coverage area when deemed unfeasible or unsafe. The allowance for direct attach connection was created for systems requiring specific non-tampering needs or to support devices that only offers screw-type connections.
The ANSI/BICSI D005 (draft) recognizes that ESS devices (security cameras, intrusion detection devices, access control) are not located in the same coverage areas as a user-administered outlets for data and telecommunications (computer and phone)When planning the location of these ESS devices, the locations are deemed for specific applications – such as cameras located in ceilings and access control devices by a door. These are known as “facility work areas” as the the users do not determine what is plugged in at that location, but the facilities’ personnel and the application itself.
The hurdle in warranting a direct attach was formulating test procedures to meet certification requirements for these links. The Nexans Data Communications Competence Center (DCCC) tested several standards-approved Category 5e and 6 plugs attached to Berk-Tek UTP cable and found that when attached properly, these plug-ended links actually perform as well as a TIA-568 recommended standard structured cabling channel. However, since it is not configured as a channel or a true permanent link, it is recognized as a ‘modified link’ and Berk-Tek is working with test equipment manufacturers to test and characterize this set-up. In a direct attach scenario, a modified permanent link testing is recommended through the following procedure, where a patch cord is utilized on the TR side, but the horizontal cabling plugs directly into the channel adapter, eliminating the need for a patch cord. See the test set up below.