The Problem
Industrial Zebra Programming Language (ZPL) printers are the standard for label printing in manufacturing environments — durable, reliable, and purpose-built for production line use. They are not, however, built for cloud integration. ZPL printers communicate within local networks using protocols that were designed before cloud connectivity was a requirement. The result: a manufacturer using Microsoft Business Central as their ERP had no direct path from ERP to printer. Every label print job required manual coordination between the business system and the factory floor.
Across multiple factory locations, this manual step compounded. Print jobs initiated in Business Central had to be routed manually to the right local printer through the right network. Errors were frequent — wrong printer, wrong label, wrong format. Production line staff were spending time on printing logistics instead of production work.
The Constraints
No network reconfiguration. The manufacturing environment had established network segmentation for security and operational reasons. A solution requiring changes to the local network topology would have introduced security risks and required extended approvals from IT and operations. The bridge had to work within the existing network architecture.
Real-time response requirements. Production lines operate to tight cycle times. A print command initiated in Business Central needed to reach the physical printer in time to keep pace with production — not queue for a batch process or depend on a polling interval measured in minutes.
Reliable across multiple locations. The same microservice architecture had to work across factories with different local network configurations, different printer models, and different ERP connectivity parameters — without requiring location-specific code changes.
Our Approach
We built a two-component hybrid architecture: a Windows Service running locally at each factory, and an Azure-hosted cloud service acting as the communication bridge.
The local Windows Service acts as the factory-side hub. It maintains a persistent WebSocket connection to the Azure cloud service, listening for incoming print commands. When a command arrives, the service translates it into the ZPL format appropriate for the target printer and sends it directly to the printer on the local network. The Windows Service has no external network exposure — all communication runs outbound through the WebSocket connection, preserving the factory network’s security posture without requiring inbound firewall changes.
The Azure cloud service receives print commands from Business Central via standard API calls and routes them to the appropriate factory location over the established WebSocket connection. Azure Table Storage maintains the printer registry — mapping Business Central print targets to specific factory locations and printer models — and stores the audit log of all print jobs.
WebSocket protocol provides the near-instant command delivery the production environment requires. The bidirectional connection allows the factory service to send acknowledgements back to the cloud layer, giving Business Central visibility into whether print commands were received and executed successfully.
The Outcome
- Direct ERP-to-printer workflow established — Business Central users send label print commands without manual factory floor coordination
- Centralized printer monitoring across all factory locations from a single Azure-hosted management interface
- Manual printing errors reduced significantly — commands route deterministically to the correct printer for each label type
- Print command transmission measured in milliseconds — production line cycle times unaffected
Team
Engagement: 2 months, 2 engineers (1 backend/.NET, 1 Azure infrastructure).
Stack: .NET, WebSocket, Azure (Table Storage, Cloud Service), Windows Service