Electronic access control systems (ACSs) are common in our daily life for security. However, many of them are difficult to manage and hard to troubleshoot when the network goes down because they use the traditional RS485 (serial) network shown in the following figure. In this infrastructure, the RS485 network is an independent network deployed to each controller in the access control system. The power supply for the controller is typically providing DC power and is provided with a battery backup. To solve the two main problems, manufacturers have developed PoE-based access control systems that integrate into the facility’s existing IP infrastructure. Listed below are the introduction, advantages and disadvantages of the PoE access control systems.
Figure 1: Traditional Access Control System
In a PoE access control system, single-door access control panels can be located above each door as edge controllers. These controllers make all of the access control decisions just as their analog predecessors. These single-door access control panels are powered either by a midspan PoE power injector or a PoE switch to provide reliable power.
Figure 2: PoE Access Control System Connectivity
The PoE access control system can communicate with key points you installed in the access control network, such as electric door locks, biometric readers, exit request devices, etc. Here is an overview diagram of the PoE network access control infrastructure:
Figure 3: Overview Diagram of the PoE Access Control System
Compared to a traditional ACS, a PoE access control system has three main advantages listed below:
Cost-saving: This infrastructure leverages the existing IT network system and also eliminates the need for a local power source, which helps to reduce the cost.
Flexible installation: The PoE cables transmit both power and data together to each device attached to the local area network (LAN). Normally, a device must be close to an AC power outlet for optimal performance. PoE expands the flexibility of device positioning, allowing devices to be installed easily in a network without the concerns of their proximity to AC outlets. What’s more, with a PoE access control system, there is no need to spend time installing AC outlets since a PoE switch can provide power for the devices, saving time and resources.
Easy and safe management: The power over Ethernet system uses a centralized power source, allowing remotely powered devices to connect and disconnect during service reconfigurations and disruptions easily. Besides, PoE technology helps protect the whole network investment because it has established 802.3 Ethernet protocol extension and is supported by various data rates which reach up to 10 Gbps. And the PoE access control system broadens the security initiatives of a building premises by supporting CCTV devices for better surveillance. The digital signals allow the cameras to monitor who is accessing the premises.
Although there are many advantages in a PoE ACS, there is one limitation as well. The only drawback of PoE systems is the limited power transmission to the connected equipment. PoE switches or PoE injectors not only power the controllers, but also supply output power to ancillary devices such as card readers, fail-secure electric strikes, etc., which are connected to the controllers. Normally, there are two voltage limits for most PoE controllers. One is the lock output power, another is the total power output. In most cases, the total power output for all ancillary components, including the lock power, is approximately 600 mA. This requires that every component connected to a PoE controller be prescreened to determine the amperage draw so the total amperage for all components is less that the total output limits of the controller. Despite the limitation, a PoE access control system can still meet most application needs.