Selecting and designing an ACS: basic mistakes and miscalculations.
As the saying goes, only he who does nothing makes no mistakes. However, in relation to the topic of this article, there are a number of fairly common miscalculations and mistakes, avoiding which can save your nerves and the customer's. Plus, you can save money.
The first mistake I would like to mention is the lack of a common understanding of the task being solved by the customer and the contractor, or, to put it simply, a technical task for the system that has not been fully developed. Each party interprets the task at hand in its own way. Based on its own understanding, the installation company selects equipment and designs the system. And only when everything is already working, it turns out that the customer needed a slightly (and sometimes radically) different solution. Therefore, 80% of the success that the installed system will solve the tasks set correctly is a clear understanding of the issues that it must solve.
The second point: the project often does not include the possibility of expanding the system, although even upon closer examination, it is obvious that this will most likely be required at this facility. Meanwhile, it is obvious that the potential expansion of the system should be included at the initial design stage. So that later, when there is a need to add access points, cameras, security zones, a situation does not arise in which it would be necessary to relocate or add communication lines, change equipment. It may even happen that if the customer requires a function that this equipment does not support, the entire system will have to be completely replaced. If at the initial stage you take into account the possibility of expanding the system and spend a little more money in this regard, then later, when the issue becomes relevant, this will allow you to avoid headaches.
The next issue that, in my opinion, needs to be focused on is the customer's idea of the capabilities of the proposed system. There are situations when, after the system has been launched and work with it has begun, questions arise: «Isn't there such and such a function in the system?» The reasons for such situations can be different: either the customer himself heard something from someone, but did not specify, or the equipment supplier promised, implying that such a function should, of course, be in the system. In principle, some manufacturers are ready to expand the functionality to meet the customer's requirements, since technically almost everything can be done, it is only a matter of money and time. But sometimes there are requirements that simply do not fit into the ideology and concept of a given system. To avoid such situations, it is better to consult with the manufacturer once again, whose technical support exists for this purpose. But this should be done at the early stages of design, and not when the system has already been put into operation.
Another common situation is the desire to save on everything. It is not difficult to understand this desire. The installer, saving on purchases, tries to earn more. The customer, trying to pay less, begins to insist on choosing cheaper components of the system. Of course, it is not worth throwing money around. But you also need to save wisely. At the very least, the choice between saving and reliability of the system should definitely be in favor of reliability. It is even worse if, for example, the readers chosen according to the principle: the cheaper, the better, turn out to be completely incompatible with the controllers to which they are supposed to be connected. The example may be somewhat exaggerated, but, nevertheless, it is clear enough to express the essence of the possible problem.
It often happens that they choose some unique solutions for which it is difficult to even buy equipment. Or when the system is already in operation and it needs to be expanded, it turns out that the system uses cards of its own unique format, and each card costs 10 euros. And you need to buy, for example, another 3,000 cards. It is easy to calculate that for this money it may be easier to replace the entire system and use common proximity cards that cost several tens of cents.
Most of the above problems related to system design usually start to appear at large facilities with a distributed structure, large event traffic, etc. For example, an enterprise employs 6,000 people, and there are two regular tripod turnstiles at the checkpoint. And every morning people stand in line at the turnstiles for half an hour. Because when designing the system, they simply did not take into account the number of personnel and did not calculate the required throughput of the checkpoint. If these calculations had been done in advance, it would have been easy to understand that for this case either a larger number of tripods or the use of normally open turnstiles are needed.
Not so obvious, but greatly affecting the reliability of the system is the issue of electromagnetic compatibility. In our practice, there was a case when a competently and professionally installed ACS, all components of which were absolutely serviceable, stubbornly refused to work stably. As a result, it turned out that there was a powerful electromagnetic noise generator (commonly known as a «jammer») in the building, which disrupted the normal operation of not only the security system controllers, but also other electronics in the building. The customer politely kept silent about this, not considering this point important, the installers spent an additional lot of time and effort, changing the equipment and relocating communication lines. And only by chance one of the security service employees let slip that even their radio stations do not work when the noise generator is working. The problem was eventually solved, but at what cost. Having worked through this issue at the initial stage, it would have been possible to avoid unnecessary waste of time, effort and money.
Calculating communication lines is also important. For example, there are hardware limitations for the 485 interface: just over one kilometer for a certain type of cable (without using intermediate hardware signal amplifiers). They calculated the distance between the points — 700 meters. They started laying the cable. But it is not laid in a straight line, but on floors, with bends and turns, and as a result it turns out that the distance will not be 700 meters, but all of one and a half kilometers. The same thing is with the number of pairs of wires. At first they estimate: 10 pairs seem to be enough. And then, when there are not enough, they start connecting a common «ground», without delving into what can be paralleled with what. As you know, the weakest link in the system is a personal computer (PC). Therefore, special attention should be paid to the issue of distributing software components and configuring them. The performance and demands of subsystems on computing resources play a decisive role. An attempt to install a powerful video system together with an access control system and an OPS on a weak old computer may result in a bunch of complaints from the customer in the future that the system “slows down” and “freezes”.
All of the above is the manufacturer’s point of view. I would very much like to hear the opinions of those who directly design and implement the systems. It seems that such a dialogue will help to identify and solve our common problems, which will ultimately allow us to offer the customer a quality product.