The bench test 1: Count us in

IET has introduced a ReaDeREXpander unit in order to meet the "counting in and counting out" requirement while maintaining the existing door capacity of the Tower (two-door) and Integra (four-door) access control units. The RDREX can be retro-fitted to existing systems, involving minimal changes to wiring – it provides a dual card reader channel on a single reader cable.

We looked at a two-door T4000 Tower Plus along with two RDREX units and four readers: two magnetic stripe and two proximity (Wiegand). This is the basic building block, which can be either used alone or extended to build a single network of a maximum of 63 individual T4000 units. The units are linked using an RS 485 data connection, which should not exceed a total cabling run of 1.5 km.

The T4000 (single unit or system) has a 4000-card capacity. When a valid card is presented at a reader, RDREX determines whether it is an IN or OUT reader involved and signals the access control unit (ACU) accordingly.

If anti passback is enabled, the ACU considers the individual card status (IN or OUT) before un-locking the door by energising its on-board relay. The door position is constantly monitored and an alarm generated if the door is left open too long after a valid card has been read – or forced open.

Once installed, the system can be programmed using a handheld detachable LCD programmer plugged into an external socket on a T4000 control unit, using the 2m cable provided. This enables the network to be configured, doors programmed, card numbers entered, and access groups and time zones set.

Once a T4000 network is set up and tested, data needs to be entered at one ACU only since it is automatically passed to the other connected ACUs. Operators can use the detachable LCD programmer at any time to view system status, alarms and the complete system database without the need for a PC.

After initial network configuration, a host PC can be used not only to complete the programming, but also control, monitor and save system events in files. Furthermore, a single PC (or a network of PCs) can control up to eight separate T4000 networks.

The T4000 Tower Plus provides flexible access control to meet a wide range of requirements for small and large installations. It is housed in a large 1mm steel box containing the main PCB 153 x 204 mm, a separate 12v PSU PCB 110 x 62 mm, mains transformer, mains fused connector, 7Ah standby battery and tamper sensor.

The layout could have been improved by removing the standby battery bracket, thereby allowing the battery to be installed in a life-extending "terminals up" position and lowering the PSU PCB in order to provide better access to the PSU output terminals. The main PCB and RDREX units have unpluggable screwed terminal connector blocks, thus avoiding a similar problem.

The tamper sensor is quite novel in that it uses a Hall Effect device and lid-mounted magnet. Bench Test readers from the mid-90s may recall that a similar device was responsible for making a DC current measuring clamp meter a reality – a truly versatile component! Inside the T4000 ACU enclosure the sensor requires only a small slim operating magnet, which is less likely to be displaced during handling.

The PSU has a rated output of 13.8v at 2A with electronic regulation and overload protection. It has sufficient capacity to supply the electric door locks in addition to the control panel and door readers.

All the internal components are bolted securely in place using clinch-nuts in many instances, resulting in really sound construction.

The RDREX units consist of a single PCB 50 x 70mm mounted on four "sticky feet" in a plastic enclosure 41 mm (D) x 76 (W) x 100 (L). The quality of PCB construction is good.

Installing and connecting are covered in fine detail in Chapter 3 of the Installation and Operating Manual. This includes recommended types of cable and maximum cable lengths. Shielded cables are used, even for the lock connections – several earth connection studs are conveniently provided by the cable entry knock-outs in the access control unit, so that long lengths of bared screen connections can be avoided.

The RDREX units can be sited near their corresponding doors or removed from the white plastic enclosure and mounted in the ACU – spare mounting feet are supplied. In the latter case, separate IN and OUT reader cables will need to be run from the readers to the ACU – the choice is there. Particular care must be taken to connect the appropriate supply voltage for the type of reader in use: 12v for prox (Wiegand) readers; 5v for magstripe readers. Each RDREX unit is supplied with 12v and has a 5v regulator on board so it is just a matter of linking the reader's supply to the correct terminal.

Generally connecting is straightforward, following the Tower Plus Basic Connections diagram and RDREX Installation sheet. It would have been helpful if the Tower Plus (ACU) connector numbers, widely referred to in the text, were included on the Basic Connections diagram.

Before applying power, it is necessary to check that the reader jumpers in the ACU are correctly set to MS or WG. This was a bit confusing initially since there are four jumpers and eight pairs of pins on which to park them – just for two RDREX units. It pays to refer to the diagram and read the instructions very carefully and also to ensure that transient suppressors (MOVs supplied) are fitted across the door strikes. The MOV is not polarity-conscious and therefore not likely to be damaged on initial application of power.

We noticed that if the standby battery is clamped too closely to the edge of the enclosure during installation, the cover does not fit properly.

After connecting and powering up, our bench system was programmed using the detachable LCD programmer, following the excellent written step-by-step instructions. We only strayed far enough into the access control database section to enter cards in order to check that the system operated correctly, and noticed the "first card/ last card" time-saving system in operation, whereby only two cards of a consecutively numbered run need to be entered for a particular access group and time zone.

The Tower Plus Installation and Operating Manual describe in fine detail how to "install, connect, plan and configure a Tower access control system". It starts with a comprehensive description of the terms used, before getting down to the "nitty-gritty" of installation – a section well worth reading thoroughly before proceeding with the installation.

We considered that, while this is an excellent manual, it would benefit greatly by the inclusion of the relevant sales promotional sheets. These listed the system main features, including a list of general technical data, and details of the two control software packages, giving an informative system overview.

What the manufacturer says ...
With any security system – and in particular access control networks – communication or equipment failure is not acceptable. To minimise these problems, IET's controllers offer true full distributed intelligence.

   Each Tower controller is a master containing the full system database. It can operate as a standalone unit if it needs to. This means that Tower will function normally with or without a PC.

   If the communication network is broken or a unit is caused to restart, when the system recovers, the controllers poll data between each other. Each individual unit is updated accordingly without any need for a host computer.

   These ACUs can be used with short or long range proximity cards, radio frequency asset tags and a wide range of magnetic stripe, barcode and Wiegand card readers. For higher security, a range of biometric systems are available ranging from fingerprint, hand geometry, iris and facial recognition.

   The two-door Tower controller allows up to 8000 card holders and 126 units per network, Global Anti Pass Back and automatic card and timezone activated free access for selected groups of doors. Up to four Building Management units can be attached to each controller to provide for lifts or general monitoring and control.

   Both the standard software packages allow comprehensive control and management of the systems, with communication over WAN, LAN or local serial ports.

   Wintacs is a Multi Network, single workstation software and can be used with all IET networking systems. This package is also available with integrated ID card printing, encoding and an automatic floor plan option.

   Terminus is a Multi Network, enterprise wide client/server software package which allows the use of multiple workstations for multi-tenant buildings.

   The RDREX reader expander is a compact low cost module that can be used with any IET networking access control unit to provide read in/read out capability down a single reader port, thereby saving cabling and effectively doubling the reader capacity of any ACU.