An I/O counter tool in Excel for PLC and DCS projects. List the equipment, pick a device type for each item, and the tool counts the I/O, splits intrinsically safe from non-IS points, and sizes the I/O cards, spare channels and remote I/O stations for every panel and controller. Use it to prepare a control system RFQ, check a vendor’s offer, or size a system early in design.

A wrong I/O count is one of the most common reasons control system quotes come back too high, too low or not comparable. This tool gives every bidder the same clear numbers.

What’s included in the I/O counter

Equipment list: tag, description, area, panel, device type, quantity and IS flag for each item, with extra DI, DO, AI and AO columns for signals outside the typical. Room for over 1,400 rows.
Device typicals: 35 device types with I/O per device, from DOL, reversing, soft starter and VFD motors (hardwired or network) to on/off and control valves, transmitters, flowmeters, analysers, gas detectors, switches, E-stops, heat tracing, power meters, UPS and package PLCs. Edit the counts to match your control philosophy, or add your own.
Panel summary: DI, DO, AI and AO points (IS and non-IS), I/O cards, total modules, remote I/O stations, and Ethernet, Modbus and HART multidrop devices for every panel.
Controller summary: required points, cards, installed channels, spare channels and spare % for up to 10 controllers and for the whole project.
Card sizing setup: channels per card and installed spare % for each signal type, modules per remote I/O station, and a future space allowance.
Check column: flags rows with no panel, an unknown panel or device type, or a zero quantity, so nothing is left out of the count.

Built for real projects

Cards are rounded up per panel, because each panel holds its own cards. That’s how the real system will be built.
Network devices (Ethernet, Modbus and HART multidrop) are counted separately and don’t use I/O channels.
The controller figures carry straight into the Tender and Claim Control System BOQ and Control System Technical Compliance.
Works for any platform: set the channels per card to suit the system you’re specifying.

File details

Microsoft Excel (.xlsx) for Excel 2016 or later, Microsoft 365 and LibreOffice 7 or later. No macros.
Yellow cells are inputs. Formulas on the summary sheets are protected without a password, so they can’t be overwritten by accident.
Instructions sheet in every file, plus a Read Me PDF with a one-minute quick start.
Instant download after purchase. Re-download any time from My Account.
Licensed for use on your own projects. Not for resale or redistribution.

This tool is a starting point to save you time. Typical I/O counts and card sizes must be confirmed against the P&IDs, motor list, control philosophy and the selected platform before issuing a tender. It is not engineering advice.

card sizing

Control System I/O Counter Excel – PLC / DCS I/O Count and Card Sizing Tool