SCADA Historian Storage calculator
What the same data costs once it is archived rather than transported.
SCADA / OT · Interactive Operations Model
Telemetry Bandwidth Calculator
Bit rate · Daily and monthly data
Change the polling assumptions and see what the link is really carrying — point count, poll interval, payload size, protocol overhead and the number of sites sharing it. At small payloads the framing can be most of the traffic.
Values requested each cycle. Reading a contiguous block costs far less than the same count scattered across registers.
Time between cycles. With report-by-exception, use the effective update rate rather than the scan rate.
Framing, addressing, TCP/IP and acknowledgements on top of the application data. Small frequent reads carry proportionally far more of it.
Remote sites sharing the same circuit or data plan.
Start from an example: One remote site, 500 points every five seconds →
Advanced parameters1
- —Sites
- —Points each
- —Polled every
- —Overhead
- —Link
- —Bandwidth required
- —Data per day
- —Data per 30 days
- —Values per second
- —Throughput
Move a parameter and the link answers: what each poll cycle puts on the wire, how much of it is framing rather than measurement, and what that comes to in a day.
The link carries the figures you entered, in the part of the address that is never sent to a server.
Change one assumption at a time. The model updates from the same calculation used for the reported result.
Try this
Keep the number of sites and points fixed. Shorten the polling interval and watch how quickly the required link capacity changes.
How the model works
- The cycleEvery poll interval, each site reports one value for every point it is polled for. That is the whole of the traffic model: a count of values, repeated at a rate.
- The framingEach value carries protocol overhead with it — addressing, headers, checksums. It is charged per value, not per cycle, so at eight bytes of payload a 40% overhead is nearly a third of the link.
- The sitesA shared link carries every site's poll cycle. Ten sites on one radio is ten times the traffic, whatever the link was sized for when there was one.
- The dayA bitrate is hard to argue with a budget about. The same traffic over a day and a month is the number that decides a cellular plan or a satellite bill.
Need this against your real link and protocol?
We can measure what the poll actually costs on your circuit, model batching and retries, and design the acquisition so the data plan stops being the constraint.
Calculation basis 4 steps · view the method →
Values per second = points per site ÷ poll interval × sites—Application bytes per second = values per second × bytes per point—Bandwidth = bytes per second × (1 + overhead) × 8 bits—Monthly data = bytes per second × 2,592,000 seconds—
Assumptions & limitations Screening estimate for link sizing and data-plan budgeting · 6 assumptions →
This is a screening estimate. Real traffic depends on the protocol, on how many points fit in one request, on retries and keep-alives, and on whether the link carries anything else. Cellular plans also bill rounded sessions rather than exact bytes. Confirm against a measurement on the live link before committing to a plan or a circuit.
- Every point is polled on the same interval and every poll succeeds.
- Overhead is applied as a flat percentage; in reality it depends on how many points fit into one request.
- Retries, keep-alives, time synchronisation and management traffic are excluded.
- A month is taken as 30 days.
- Bandwidth is quoted in decimal bits per second, as links are sold.
- Nothing else is assumed to share the link.
Worked examples
- One remote site, 500 points every five seconds
Open with these figures → - Four sites, one-second poll on 2,000 points
Open with these figures →
What this model reveals
A link is not sized by the number of points but by how often you ask them. Polling is a rate, and every value carries protocol framing with it — charged per value, not per cycle, so at small payloads the framing can be most of the traffic. The model separates the measurement from the overhead, and the sites from each other, so you can see which part of the link you are actually paying for.
Go deeper
SCADA, Telemetry & Industrial Monitoring challenge
Twelve questions on polling, report-by-exception, protocols and the OT/IT boundary.
Power & Utilities expertise
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