Services & Capabilities
John Herold is a controls and field service engineering firm based in Decatur, delivering four core capabilities across industrial automation and mission-critical data center construction projects nationwide: controls engineering, field service engineering, commissioning, and systems integration.
Controls Engineering
John Herold develops and deploys PLC, SCADA, HMI, and DCS architectures tailored to the demands of the project — not templated solutions pasted in from the last job. Work includes I/O design, sequence of operations development, control narrative authoring, and panel design coordination with fabricators. The team writes logic that operators can actually follow and that field engineers can troubleshoot at 2 a.m.
Field Service Engineering
On-site field service work covers installation support, loop checkout, field device configuration, and punch list resolution from startup through owner acceptance. John Herold field engineers work directly alongside electricians, instrumentation techs, and MEP subcontractors — providing real-time technical direction to keep commissioning milestones on schedule. When issues surface during energization, the team diagnoses at the source rather than escalating paperwork.
Commissioning
Commissioning services span FAT and SAT coordination, pre-functional and functional testing, and integrated systems testing (IST) support. John Herold builds commissioning plans that align with the sequence of operations, so test scripts verify the logic as written — not a generic checklist. The team communicates directly with EPCs, owners' engineers, and AHJs to keep documentation and acceptance criteria moving in parallel with field work.
Systems Integration
Integration work focuses on connecting control systems, BMS, power monitoring, and third-party equipment across communication protocols — Modbus, BACnet, Ethernet/IP, and OPC-UA among them. John Herold coordinates MEP scope boundaries, resolves interface conflicts before they become RFIs, and validates end-to-end data flow from field device to operator workstation. The goal is a system that performs as the sequence of operations describes it, every time.
Project Types & Environments
Industrial Automation
Manufacturing facilities, process plants, and industrial infrastructure where PLC/SCADA reliability and precise control logic directly affect production uptime and safety.
Mission-Critical Data Centers
New construction and expansion projects for colocation and enterprise data centers, where BMS integration, MEP coordination, and commissioning rigor are non-negotiable from day one.
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