Reference

Site management for motorhome sites: power, water, booking and card payment without on-site staff

EPSIA developed a software platform for the automated management of motorhome sites for Modusan GmbH, Berlin. At each location, a local controller links booking, card payment and receipt printing with power and water pedestals, showers, access points and other field devices.

Guests can book, pay for and use their pitch and utilities themselves. Locations with different equipment use the same software and are adapted to their existing hardware through their own configuration. The system has been in use at seven locations since the beginning of 2026.

7locations with the same software and location-specific configuration
84sockets with consumption-based billing
80pitches bookable automatically
1Modbus line for the field devices of a location

The pedestals the controller runs: on the left the terminal pedestal with display, card reader and receipt output, on the right a power and water pedestal with keypad.

The case study follows the project in seven steps: assignment, system design, power and water, booking and payment, configuration, operation and result.

1 Assignment: Utilities and billing without permanent on-site staff

Operators of motorhome sites want to offer power, water and other services without having to keep staff on site permanently. Conventional solutions often rely on coin-operated machines or require manual steps on site.

Modusan develops and manufactures utility pedestals including their electrical equipment. In 2024, Modusan commissioned EPSIA to develop common control software for the sites.

The aim was a software platform that can be used at different locations with whatever hardware is installed there. Development was initially carried out on a time-and-materials basis in several clearly defined packages.

2 System design: One local controller runs the location

Each motorhome site has its own local controller based on a Raspberry Pi running Linux and the EPSIA platform iSDK. The controller manages the local booking database and executes booking, billing and switching logic directly on site.

This keeps the core functions of the site available locally; individual switching and booking operations do not depend on a permanent connection to a remote server.

Schematic drawing of the process components of a motorhome site: on the left the controller on a Raspberry Pi with booking and switching logic, MariaDB database and web interface, above it in the VPN the operator's web interface and a deployment server for updates; below it, via USB and serial, the card payment terminal through an MDB adapter and the receipt printer; on the right, on a Modbus RTU line over RS-485, the touch display as booking terminal, power pedestals with meter, cut-off value and enable per socket, a water pedestal with keypad, entrances and showers with keypads, time switches on a weekly schedule and a reset output for the card terminal adapter. — The process components of a motorhome site: one controller per site, one Modbus line for all field devices, plus card payment terminal and receipt printer — the configuration determines which devices exist.

The system connects a range of components:

Controller: Raspberry Pi with Linux, iSDK and a local MariaDB database. Separate software modules for each device type poll and control their devices cyclically.
Fieldbus: Modbus RTU over RS-485 connects power and water pedestals, keypads, access points, showers, timers and the booking terminal.
Booking terminal: A Modbus-capable touch display shows 13 operating screens. The controller determines the sequence and content; new display firmware can also be transferred over the fieldbus.
Payment: A card terminal is connected via an MDB adapter. If the controller detects a fault in the adapter, it can restart it through a switchable output.
Receipt printing: A thermal printer is connected to the system via a serial interface.

View into an open pedestal: several green bus modules with relays and LEDs on DIN rails, connected by orange patch cables for the RS-485 bus, behind them blue control wires; the manufacturer's print on the boards is obscured. — Inside a pedestal: the bus modules hang on a shared RS-485 line and supply the controller with meter readings; the controller writes back the cut-off value and enable signal.

3 Power and water: Providing booked services automatically

The software links a booking directly to the technical services at the pitch.

Each socket on a power pedestal reports its current energy meter reading. When a guest books a certain amount of electricity, the controller calculates a cut-off value from the current meter reading and the purchased amount of energy and enables the assigned socket. Once the booked amount of energy has been used, the supply is switched off automatically.

The software also assigns the socket. For each pitch, the controller knows which power pedestals and sockets can be reached and assigns an available connection. The pedestal and socket number are printed on the receipt.

For water, showers and access points, the guest uses a personal access code. The controller checks the authorisation and enables the service according to the booking – for example water up to the booked number of litres, or access for a defined period.

Time-controlled functions such as lighting or irrigation can also be controlled using stored weekly schedules.

A stainless steel water pedestal being installed at a pitch, dug-up soil and hoses in front, construction fencing behind: a small keypad with display at the top, the tap on the side, a sticker on the door with drinking water instructions; the manufacturer's name is obscured. — A water pedestal being installed: the guest enters the code from the receipt on the keypad, and the valve opens up to the number of litres booked.

4 Booking and payment: From the terminal to checkout

The entire booking process can be completed on site without any intervention by staff.

Schematic sequence of a booking in seven steps: choose pitch, choose services, reserve with a four-digit code, card payment, receipt, use on site with socket cut-off and code entry on the keypad, departure at checkout time. A return path leads back to the start if payment is cancelled; a branch shows adding services with the code at the terminal, back to payment. — A booking in seven steps: only the confirmed payment makes the booking valid, and at checkout time the controller closes it itself.

The process covers:

Booking: The guest selects a pitch, length of stay and additional services such as power and water. Prices, limits and available booking steps come from the local database.
Payment: The controller sends the total amount to the card terminal. The booking only becomes binding once payment has been confirmed. Unpaid temporary bookings are discarded automatically after a defined period.
Receipt: The thermal printer produces a receipt with the booked items and the tax rates shown separately. It also shows the assigned power pedestal and socket and a four-digit access code. A separate section can be displayed visibly in the vehicle.
Extending a booking: With the access code, the guest can call up the existing booking again, check the remaining credit and book further nights, power or water.
Checkout: When the booking expires, the controller closes the session, deactivates the associated utilities and removes access codes that are no longer needed.

5 Configuration: Different locations with the same software

The seven locations differ considerably in size and equipment. A location can have between three and twenty pitches, one or more power pedestals, different numbers of sockets and, optionally, access points, showers, water supply and time-controlled functions.

These differences are not handled through separate software versions. Each location has its own configuration that describes its technical equipment.

This includes, among other things:

pitches and their assignment to utility points
power pedestals, bus addresses and sockets
assignment of reachable sockets to individual pitches
water points, access points and showers
time-controlled functions and weekly schedules
services offered with prices and tax rates
operator details for receipts and billing

A setup tool generates the data required for each location from this configuration. The control software itself remains identical at all locations.

Five stainless steel supply pedestals being assembled in a workshop, each open on a hand truck: rows of circuit breakers, residual current devices and terminals wired in blue, with protective film on the panels. — Pedestals being assembled at the manufacturer: the electrical work comes from the customer, the software that switches and bills each socket from the EPSIA team.

6 Operation: Supporting seven locations centrally

The local controllers can be reached via secure network connections. A web interface gives the operator a central overview of locations, pitches, utility pedestals and sockets.

Depending on their permissions, users can create or end bookings, adjust prices and check printer and payment functions, among other things.

New software versions are distributed to the individual locations via a central deployment server. Control of the field devices and the local booking logic remain on each controller.

7 Result: Seven differently equipped locations with the same software

Since the beginning of 2026, the site management system developed by EPSIA has been in use at seven locations in Germany.

In total, the software manages 80 pitches.
23 power pedestals with 84 sockets are integrated into the system.
7 water pedestals are connected to the local controllers.
Guests can book and pay for their pitch and utilities themselves.
Electricity is controlled on a consumption basis via the amount of energy actually supplied.
Different location equipment is handled through configuration.
All seven locations use the same software base.

What does this project stand for?

The project shows a system with a hardware connection outside classic mechanical engineering. EPSIA combines local field devices, booking logic, payment, receipt printing, data storage and central management into one software system.

The software is not hard-coded for a single location. New locations with different equipment can be integrated into the same software platform through their hardware and service configuration.

This turns a custom control system for a single site into a reusable platform for several locations.

How long did it take until the system went into use?

Modusan commissioned EPSIA to develop the control software in July 2024. Development was carried out in several packages.

In 2025, the booking and payment process was developed further and the user interface was revised, among other things. Since the beginning of 2026, the software has been in use at seven motorhome sites.

How does a project with a hardware connection start at EPSIA?

A project with a hardware connection can start at EPSIA with an architecture review at an agreed fixed price. EPSIA analyses field devices, communication paths, data flows, software components and the requirements for later operation.

The result describes the components needed, how they work together and a sensible order for implementation. On this basis, a functional specification and a fixed-price offer for the subsequent development can be prepared.

More about this service under Software development for systems with a hardware connection.

Key facts

Customer: Modusan GmbH, Berlin
Service: Hardware-related systems
Industry: Utility technology and digital infrastructure for motorhome sites
Period: since 2024, in use at seven locations since early 2026
Technology: C++, Qt, iSDK, JavaScript, Python, MariaDB, Modbus RTU, RS-485, MDB, Raspberry Pi, Linux, WireGuard.