SCADA software is priced by what the vendor counts, and that decides the total more than the list price does. Tags, operator clients, drivers, servers and modules each get charged differently, so two quotes with the same headline figure can describe very different systems.
This post is for whoever is comparing quotes: a plant or utility manager, or an integrator specifying for a client. The one question is what you are actually paying for, and how to line two quotes up so the comparison means something. If you are still getting oriented, what SCADA is covers the parts and how they fit.
The licence metric decides the price
Every vendor picks something to count. The list price only means something once you know what is being counted and how many of it you have. These models all exist in the market, and a single quote often combines several.
Tags or I/O points
You buy a band: a few hundred tags, a few thousand, tens of thousands. It is easy to start small, and every time the plant grows past a band edge the price steps up. Find out what counts as a tag (a raw device address, an alarm, a calculated value, a history point) because definitions differ.
Concurrent clients or seats
You pay for operator screens. A concurrent model counts how many are open at the same moment, so forty operators on three shifts at six terminals need six. A named model counts people or machines that are allowed to log in. Ask whether phones, tablets and wall displays count as clients.
Devices or drivers
Some vendors charge per protocol, per device, or per connected controller. A plant with one PLC brand pays little and a plant with five brands pays more. This is where a missing driver turns into a surprise, so ask for every protocol your equipment speaks to be priced explicitly.
Servers and gateways
One licence per server, per gateway or per site. This is simple to read. It matters when you need a second server for a remote site, a test system or a hot standby, so ask whether those are licensed again.
Functional modules
The base is priced low and the historian, alarm notification, reporting, a mobile client or a scripting layer are added one by one. Each can be reasonable alone. The sum is what you compare.
Engineering or development seats
Some vendors charge for each person who builds screens and logic. The charge looks small until a contractor, a second engineer and a laptop for the field are all involved.
Perpetual versus subscription
A perpetual licence is bought once. The software you bought keeps running, and an optional annual plan covers support and, often, new versions. A subscription is paid every year for as long as you use the product.
The difference shows up on a timeline:
| Perpetual | Subscription | |
|---|---|---|
| Year 1 | The largest payment | A smaller payment |
| Year 5 | Little or nothing beyond an optional support plan | Five annual payments made |
| If you stop paying | The software keeps running, and support or upgrades lapse | The licence usually ends, so check what the system does |
A subscription spreads the cost and can include upgrades, which suits some budgets. A perpetual licence turns the cost into a one-time purchase, which suits others. What separates them is the last row: what does the running plant do on the day the payment does not arrive? Get the answer in writing, and ask it for the system as it will be after a power cut and a restart.
Support and upgrade plans
With a perpetual licence the annual plan is usually a share of the licence value, charged every year. Because it scales with what you bought, a small system pays a small amount. Before you accept the percentage, ask three things:
- What lapses if I do not renew: support only, new versions, or the licence itself?
- Does the plan include moving to the next major version, or is that a separate purchase?
- What is the response commitment, and who answers: an engineer, or a ticket queue?
Ask for the plan's yearly cost as a number on the quote. A percentage on its own makes the comparison harder.
Costs outside the software quote
The software line is rarely the whole project. Count these separately, because they can sit with a different party.
- Databases and operating systems. Some stacks need a database server licence for history, or a specific server OS, and that is a separate purchase. Ask what the historian stores to and whether a licence is needed.
- Server hardware. One or more servers, plus storage sized for the history you intend to keep.
- Redundancy. A second server or gateway, with the licence terms that come with it.
- Integration labour. Building screens, tags, alarms and reports, then commissioning and testing. On many projects this is the largest line.
- Training. Operators and maintenance staff both, and the time it takes them.
If a quote lists only the software, you have one line of the budget. Ask the integrator or vendor for the rest as estimates, even rough ones.
How to compare two quotes
Price the system you will have in five years
A quote built for day one is easy to win and easy to regret. Write down what the plant will probably look like in five years: more tags, more operators, another protocol, a historian you do not need yet. Price both vendors for that system.
Ask what growth costs
Put specific additions to each vendor and ask for a number:
- What does it cost to add 500 tags?
- What does it cost to add two more operator screens?
- What does it cost to add one more protocol?
- What does a second server for standby or a remote site cost?
The answers show you where the metric bites. Some additions are free on one quote and a line item on the other.
Put the support plan in as a number
Add the yearly support cost for each year you are comparing. Then decide whether you would actually buy it every year, and compare against that.
Questions to ask every vendor
- What do you count? Tags, clients, drivers, servers, modules, engineers: say which of them meters my plant.
- What does it cost to add 500 tags, two screens, one protocol? Get each as a figure.
- Perpetual or subscription, and what does the plant do if I stop paying? In writing.
- What does the support plan cost per year, and what lapses without it? Support, upgrades, or the licence.
- Is a major-version upgrade included, or priced separately?
- Do I need a database or OS licence from someone else?
- Are test, standby and remote-site systems licensed again?
- Is every protocol I use included, and what does one that is not cost?
- What is the activation model? A file on the machine, or a check against a server.
- Are engineers and designers charged?
Frequently asked questions
Is SCADA software priced per tag?
Sometimes. Per-tag or per-I/O-point bands are one common model, and in that model the band decides the price. Others charge per operator client, per server, per driver or by subscription, and many mix two or three of these. Ask which one meters your plant.
Is perpetual or subscription SCADA cheaper?
It depends on the horizon. A perpetual licence costs more in year one and then mostly stops, apart from an optional support plan. A subscription costs less up front and is paid every year, so over five or ten years the totals can cross. Price both for the same number of years.
What happens to my SCADA if I stop paying?
Under a subscription, the licence normally ends and the system stops or goes read-only, so check the terms. Under a perpetual licence the software you bought keeps running, and what lapses is usually support, updates, or both. Ask the vendor in writing which one applies.
How much of a SCADA project is the software?
It varies by project, and there is no honest single figure. Integration labour is often the largest line, and hardware, database and OS licences, redundancy and training add to it. Ask for the software quote and an estimate of the rest separately.
One worked example: a published price list
Raylux publishes its price list, so it makes a plain example of the models above. Every figure here is on the pricing page, where a configurator quotes a plant.
The licence is perpetual. The $995 Base Gateway includes all eight protocols, OPC UA as both client and server, and unlimited tags, devices and engineering seats. What Raylux does meter is concurrent operator clients. The Spectrum HMI module is $1,950 with two clients included, then $195 for each client up to nine, with capacity tiers beyond that. Two screens with the gateway come to $2,945. The historian is $1,750, and reporting and alarm notification are priced add-ons.
The optional Support Plan is 20% of licence value a year, which is $199 a year for a base gateway alone. If it lapses, the licence keeps working. What you lose is the response commitment, the phone line and upgrades across a generation. Updates within a generation come with the licence either way.
The comparison page lists, item by item, how this differs from a conventional stack, without naming any vendor. Whatever you are comparing, the method above works on it: price your five-year plant, ask what growth costs, and get the support plan as a number.