The bench test 2: Access for all

What our experts say …

One of the least exploited areas in security installation is that of smaller scale access control units. While the CCTV market receives the great majority of attention, small businesses and even residential properties represent an access control market which as yet is largely untapped.

This is the thinking behind TDSi's MicroGarde unit, which aims to provide a simple option for access control, and consequently an expansion of the average installer's potential business opportunities.

The design and installation of an access control system, using the MicroGarde Access Control Units (ACU) as the basic building "bricks", should be a straightforward task.

A Microgarde access control system can comprise of up to eight Access Control Units administered by a PC either locally, using RS 232/ RS 485 connections, or remotely via a dedicated TCP/IP link.

One door and two door versions of the MicroGarde ACU are available, giving 1 to 16 door system capability.

We looked at the single door version (MG1) along with one proximity card reader, exit button and door strike relay connected.

The MicroGarde ACU can support a range of readers including Proximity, Magnetic, Infrared and Biometric/Mifare. Two readers per door may be installed for anti-passback control, giving a higher level of security.

The system, irrespective of the number of controllers used, supports up to 2000 individually identifiable cards.

The MG1 ACU has two output relays, each having a single pair of clean (volt-free) contacts, rated at 2A, 30 Vdc/0.4A, 125 Vac. These can be configured NO or NC for controlling the door release mechanism (lock or strike), giving the option of "fail safe" or "fail secure" operation, also for door alarm output, using the spare relay which can be programmed to follow the input, or annunciate alarms.

The MG1 log holds the last 2000 events, such as card addition and deletion, door alarms and card transactions.

The MicroGarde ACUs do not have a built-in power supply and the manufacturer recommends the use of separate 10 – 14v PSUs for controller and lock, for maximum reliability. A one ampere current rating is considered sufficient for an ACU and its readers.

Should a complete power down occur, the programmed and stored card information is held by an on-board lithium battery which should last for five years.

Construction

The MicroGarde Access Control Unit electronic components are mounted on a single PCB measuring 110 x 77mm which is firmly secured to a 1mm steel base. There is space for an optional input/output module which offers four additional inputs and two additional relays. The base has steel clinchnuts suitably placed for securing the PCB and I/O module in position – engineering threads are used throughout.

The plastic cover has easily removable cable entry sections along three sides and is held in place by two bolts engaging in brass nuts. The lack of an on-board power supply results in a smaller unit which is outwardly neat and unobtrusive. Refreshingly, there are no plastic nuts or self-tapping screws in sight!

A detachable thin plastic sheet clips neatly over the PCB: its main function is to carry the screwed connecting terminal markings which are helpfully colour coded for the DC supply input and reader connections. There are openings in the sheet for viewing the UID number (unique identification), unit system number (0-9) , 5v power on LED, communications busy LEDs, the communications terminating switches and tamper switch operating spring. The sheet will need to be removed only for changing the lithium memory back-up battery or the 1A fuse.

Slots have been cut in the edges of the steel baseplate at regular intervals for earthing the cable screens, by wedging them into the slots. We consider that the addition of screwed terminations for the screens would improve long term reliability.

Quality of PCB construction is of a high standard, as generally seen in security equipment, resulting in reliable operation.

Installation

The MicroGarde ACU has 3 fixing points, avoiding problems with uneven mounting surfaces – screws and plugs are provided.

TDSi provide a list of recommended cable types along with maximum cabling lengths, where appropriate. Screened cables are specified for the power supply, readers, RS 232 and RS 485 communications. The manufacturer also makes the point that the screening should be earthed at one end only, in order to avoid earth loop currents caused by earthing points being at different electrical potentials. Multiple earthing can cause serious interference problems.

Suppression capacitors are provided for the mains supply to the PSU, and diodes for the locks. A diode should be connected in parallel with each lock coil in order to suppress the voltage spike induced in the coil each time the lock relay contacts open. It is vital that the diode is connected in the right direction; if not, it will blow the first time it is switched on (a bit like a fuse), but will probably go unnoticed, leading to early failure of the coil/relay contacts. A diode can be used only with DC supplied locks; an MOV (metal oxide varistor) must be used with AC supplied locks.

The ACU connecting blocks are of the better quality 'pull-up' type which have parallel jaw clamps. The blocks can be removed for ease of installation, if preferred. The connecting blocks do overhang the edges of the PCB and so need a bit of support if wired in place, to avoid undue strain on the PCB.

When each ACU is fully connected to its door lock, door sensor, reader(s)/ exit button and power supplies, final hardware checks can be carried out prior to setting up the communications. If the communications are already connected, they can be easily unplugged at the ACU without affecting local operation.

Our controller, reader, exit push (press-to-close), strike relay and door sensor were connected and successfully tried out on the bench before being connected to the communications link (RS 232) and allowed to shake hands and talk to the PC.

Instructions

The MicroGarde ACU wiring diagrams, accompanying notes, final hardware checks and software installation are all printed on one and three quarter sides of a single A4 sheet of paper - this includes the cable list, technical specification and system requirements. It's generally clear and informative in spite of the small print. In the words of TDSi: "All you really need to successfully install the product," as we subsequently verified.

The Instructions did refer to "....the Manual on the CD" which was safely locked away in the supplied CD along with the default name and password required to access the CD! We eventually found that the manual is contained in the Help files.

We discovered that the single A4 sheet was more applicable to the tested version, compared to the manual, particularly in respect of the position of the ACU indicating LEDs.

What the manufacturer says ...

Whether you're a distributor, installer or end-user, MicroGarde has been designed to deliver access control and increased security at minimal cost. It has been specifically targeted at customers that want to introduce greater security measures to protect their staff and premises at an affordable price.

Virtually every organisation in the world is a potential user of an access control system, and security is at the forefront of everyone's thinking. The market for access control continues to expand with the installation of new systems, increased risk, technology changes and growing awareness of the need for security.

MicroGarde has been designed to be the most cost effective 1 door/2 reader controller on the market, ensuring access control can be introduced regardless of the size of company or requirement.

TDSi has taken the complexity out of access control for new users. MicroGarde uses the latest technology and manufacturing methods to ensure minimal cost of ownership and efficient return on investment for the end user.

MicroGarde includes a built in RS232 to RS485 converter and fault tolerant RS485 phase reversal to minimise installation time and fault finding. In addition, the software automatically configures the controllers that are connected and guides the user through the initial setup to allow end users to concentrate on their business activities rather than the usual IT issues associated with an access control system.

The system is also scalable and expandable and can integrate with the entire TDSi product range. This allows the system to grow as the customer's business grows.

Every TDSi MicroGarde unit is supplied with free PC software complete with an on-line help system. MicroGarde is available with or without a PSU and a simple MicroGarde Starter Kit can also be ordered providing everything needed to get started and includes 1 MicroGarde unit, 1 proximity reader, communications lead and 10 proximity cards.

MicroGarde is already making its mark within the security industry having been recognised as a Finalist in this year's BSIA Security Industry Awards in the category of Best New Access Control Product.