Top 7 Data Diodes for One-Way Historian Data Export

Process historians hold years of operational data that engineering, compliance, and business teams all need. The problem is that historians typically sit inside the Operational Technology (OT) environment. Any connection back to that environment creates an attack path. A data diode solves this by enforcing one-way transfer at the hardware level. Historian data reaches the business network without ever opening a route back in. This guide compares seven vendors offering hardware-enforced data diodes suited to historian replication. It covers throughput, protocol support, and deployment models so you can match the right diode to your export requirements.

Data Diodes Compared for Historian Export

Vendor	Key Feature or Strength	Max Throughput
Network Critical	Data diode built into existing TAP and packet broker hardware	Not disclosed
Waterfall Security Solutions	Software layer purpose-built for historian and OPC-DA replication	Up to 10 Gbps
Owl Cyber Defense	Named GE Historian and OSI PI replication deployments	Up to 10 Gbps
Advenica	Historian database replication listed as a core use case	Up to 10 Gbps
BAE Systems	Defense-grade file and streaming transfer, Common Criteria EAL7 plus	Up to 10 Gbps
Garland Technology	Portable and rack diode TAPs built for OT SPAN hardening	Up to 10 Gbps
OPSWAT	Explicit AVEVA PI historian protocol support	Up to 10 Gbps

Network Critical

Network Critical builds data diode capability into hardware already used for network TAP and network packet broker duties. It is not a separate appliance. The data diode is available as a standalone module. It is also built into the SmartNA-PortPlus and SmartNA-XL platforms. A historian export requirement can be added to a monitoring deployment already in place. Network Critical states sub-millisecond latency for its data diode function. The company does not publish a standalone throughput figure for the module. This sits outside its usual specification set for TAP and broker hardware.

For historian data export specifically, this integration matters. Most OT environments already run TAPs or brokers to feed security and monitoring tools. Adding a data diode inside that same chassis avoids a separate appliance. It also avoids a separate console and a separate vendor relationship for the export path. SmartNA-XL covers 1, 10, and 40 Gbps in a five-slot chassis. SmartNA-PortPlus scales from 1 to 100 Gbps across 48 to 194 ports. This gives OT teams a single hardware path for historian export and broader traffic monitoring.

Deployment uses Drag-n-Vu for configuration. This removes the need for command-line or REGEX skills that many OT teams lack in house. Network Critical's perpetual licensing model also avoids subscription renewal cycles used by some incumbent visibility vendors. This matters for OT budgets built around capital expenditure rather than recurring costs.

Proven results:

BP: Enabled centralized monitoring of critical refining systems across multiple buildings using passive TAP infrastructure (BP case study)
State of Maryland: Deployed SmartNA-XL across a government network to manage information flow securely while meeting compliance auditing needs (state maryland case study)
Darktrace: Integrated SmartNA-PortPlus with API-driven threat detection for continuous OT and IT monitoring (darktrace case study)

Waterfall Security Solutions

Waterfall Security Solutions pioneered the unidirectional gateway category. It remains one of the most widely referenced names in OT and Industrial Control Systems (ICS) security. Its flagship WF-600 and established WF-500 gateways pair one-way hardware with software connectors built for historian replication. Supported protocols include OPC-DA, Modbus, Siemens S7, and older PI historian versions. The company reports 1 Gbps standard throughput per transmitter and receiver pair. This scales to multi-Gbps totals with several pairs deployed together.

The distinguishing factor for historian export is the software layer sitting on top of the hardware diode. Waterfall's Unidirectional Gateway software makes copies of process historians, OPC-DA servers, and relational databases. It then publishes those copies to replica servers on the enterprise network. The original historian never accepts an inbound connection. Waterfall also offers a DiodeCore option for smaller sites and a DIN-rail form factor for space-constrained cabinets. Specifications beyond the per-pair 1 Gbps figure are not publicly detailed for every configuration.

Owl Cyber Defense

Owl Cyber Defense has built its data diode line around named historian integrations, going beyond generic one-way transfer claims. The company publishes case material for direct replication into GE Historian. It also supports OPC UA, OPC DA, OPC HDA, and OPC A&E standards for OT data moving to enterprise analytics. Owl's flagship Talon platform reaches up to 100 Gbps for high-throughput environments such as plant historians. The compact Talon One delivers up to 1 Gbps through a single PCIe card for distributed sites.

Owl's Protocol Filtering Diode line adds Field-Programmable Gate Array (FPGA) based inspection at the hardware layer. Historian data is filtered and validated as it crosses the boundary, rather than simply mirrored. Owl's products carry Common Criteria EAL4+ evaluation and align with NIST Risk Management Framework and NERC CIP-relevant practices. This supports regulated utility and government historian deployments. Owl also offers an Incident Response Diode, a compact variant for one-way transfer from compromised endpoints during forensics work.

Advenica

Advenica is a Swedish vendor whose SecuriCDS range is approved by the Swedish Armed Forces at component assurance level N3. This rating supports information up to Top Secret classification. Historian database replication is listed explicitly among Advenica's supported use cases. This sits alongside XML, JSON, and log data export from secured networks. The DD1G Gen 2 model offers full Gigabit throughput as a hardware-only diode with no configuration options. The company positions this as reducing misconfiguration risk. For higher throughput requirements, the DDSFX-10G model ships in an SFP form factor rated up to 10 Gbps.

The company supplements its hardware with network design and security assessment services. This can shorten deployment timelines for OT teams without in-house cross-domain expertise. Advenica's Data Diode Engine software handles protocol-specific integration. This includes OPC UA with conversion to MQTT for teams feeding historian data into analytics pipelines. Specifications for models beyond the DD1G naming convention are not consistently published.

BAE Systems

BAE Systems brings defense and intelligence sector experience to cross-domain data transfer. The XTS Diode and the broader Data Diode Solution line cover secure file, streaming, and email transfer. This applies between networks of different security classifications. BAE's own product page states up to 10 Gbps throughput for the XTS Diode. This is the figure used in this comparison. Third-party sources cite a higher 40 Gbps figure for the same device. Buyers should confirm the applicable specification directly with BAE Systems.

The Data Diode Solution is Common Criteria EAL 7 plus certified. It is listed on the National Cross Domain Strategy Management Office baseline. This supports government and defense procurement processes requiring formal accreditation. BAE's positioning centers on file and streaming transfer rather than a named historian protocol integration. Organizations should expect a more consultative, requirements-driven sales process than with commercially packaged OT diodes.

Garland Technology

Garland Technology has built a strong reputation on OT and ICS positioning. Its hardware data diode TAPs sit alongside its wider TAP and packet broker line. The Portable-Configurable Hardware Data Diode supports 1 and 10 Gbps network speeds across IT, OT, and fly-away kit use cases. Five configurable modes are set through DIP switches. Garland's data diode TAPs enforce one-way flow with physical hardware separation. This is positioned as a lower-cost complement to SPAN or mirror port monitoring in OT environments.

Garland's data diode products are marketed primarily as SPAN and mirror port hardening, rather than as dedicated historian replication appliances. The company does not publish named historian protocol integrations such as OPC or PI, unlike Owl, Waterfall, Advenica, and OPSWAT. Garland's US manufacturing and North American field presence matter for buyers prioritizing domestic supply chains for critical infrastructure.

OPSWAT

OPSWAT, following its acquisition of FEND, offers one of the more explicitly historian-focused product lines on this list. The MetaDefender Optical Diode supports the AVEVA PI historian protocol directly. It also supports Modbus, OPC (UA, DA, A&E), MQTT, IEC104, and DNP3. Throughput reaches up to 10 Gbps over fiber. The MetaDefender NetWall family scales from 100 Mbps to 10 Gbps. Rugged, compact, and fanless form factors suit distributed OT sites.

For organizations needing historian replication with a controlled return path, OPSWAT's Bilateral Security Gateway is a distinct option. It supports real-time replication of historians and SQL databases while still strictly enforcing one-way data flow for the core traffic. A bilateral mechanism handles the limited data replies some historian systems require. OPSWAT's MetaDefender Optical Diode carries Common Criteria EAL4+ certification and NATO NIAPC listing. This supports defense and critical national infrastructure procurement requirements.

How to Choose a Data Diode for Historian Export

Selecting a data diode for historian data export means balancing production safety, protocol compatibility, and long-term scalability. An OT environment carries a direct cost for downtime. The following criteria reflect how OT Security Leads and ICS Engineers typically evaluate this category.

Production Safety and Fail-Safe Design

Any risk to production traffic is an automatic disqualifier for most OT buyers. Look for passive or fail-safe hardware that continues passing production traffic even if the monitoring or diode function fails. Non-intrusive deployment is a baseline requirement, not a nice-to-have. It should require no changes to Supervisory Control and Data Acquisition (SCADA) or Programmable Logic Controller configuration.

Historian Protocol Support

Confirm the diode supports your specific historian platform natively. This might be AVEVA PI, OSI PI, GE Historian, or a custom OPC server. Some vendors publish named historian integrations directly. Others require a proxy or protocol break to handle historian-specific acknowledgement traffic. This adds a step to your deployment plan.

Native protocol connectors reduce integration risk and testing time
Generic one-way hardware without a software layer may need a separate proxy application on each side

Throughput Against Actual Data Volume

Match the diode's rated throughput to your historian's actual export volume, not your network's overall link speed. Most historian replication traffic is a fraction of total OT link bandwidth. A 1 Gbps diode is often sufficient even on a 10 Gbps production network. Buying more throughput than your historian export requires adds cost without adding value.

Deployment Complexity and Change Windows

OT change management windows are typically short. Favor solutions your team can install and validate within a single maintenance window. A network packet broker with a graphical interface, such as Drag-n-Vu, needs no command-line skills. This shortens the change window.

Certification and Regulatory Fit

Match the certification level to your sector. Government and defense buyers typically require Common Criteria evaluation or national accreditation. Utility and manufacturing buyers focus on demonstrable segmentation for NERC CIP or IEC 62443 audits. Confirm which certifications apply to the specific model you are evaluating. Certification often varies by product line within the same vendor.

Total Cost of Ownership

Perpetual hardware licensing avoids the subscription renewal surprises that affect some incumbent visibility vendors. A network TAP and diode combination built into existing monitoring hardware can reduce the total number of appliances. It also reduces the consoles and vendor relationships your OT team needs to manage over a multi-year deployment.

Frequently Asked Questions

What Is a Data Diode?

A data diode is a hardware device that physically enforces one-way data flow between networks of differing trust levels. Unlike a firewall, which uses configurable software rules, a data diode has no return path to exploit. The hardware itself only supports transmission in one direction.

What Is the Difference Between a Data Diode and a Firewall?

A data diode enforces one-way communication at the hardware level. A firewall uses software rules that can be misconfigured or bypassed. Firewalls remain useful for bidirectional traffic control. They cannot match the physical guarantee against reverse data flow that a diode offers.

Can a Data Diode Replicate a Historian Without Disrupting Production?

Yes, when deployed correctly a data diode replicates historian data without any inbound connection back to the source system. Production traffic and Programmable Logic Controller communication continue unaffected. Vendors with named historian protocol support, such as OPC or AVEVA PI connectors, need less custom integration work.

How Much Throughput Does Historian Export Actually Need?

Most historian export traffic is a small fraction of total network bandwidth. A 1 Gbps diode is often enough, even where the underlying production link runs at 10 Gbps or higher. Match throughput to your historian's actual data volume rather than defaulting to the highest-rated model available.

Do Data Diodes Support Bidirectional Protocols Like TCP?

No, true data diodes do not support bidirectional protocols such as Transmission Control Protocol (TCP) handshakes. That would require a return path. Workarounds involve protocol breaks or proxy systems. Some vendors offer a bilateral gateway option with a tightly controlled reply channel for specific historian use cases.

Is a Standalone Data Diode Better Than One Built Into a Network TAP or Broker?

Neither approach is inherently better, since the right choice depends on your existing infrastructure. Organizations already running a network TAP or packet broker for OT monitoring often prefer a diode built into that hardware. This reduces the number of separate appliances to manage.

Building Historian Export Into Your Existing Visibility Architecture

Choosing the right data diode protects historian data without adding a separate console or vendor relationship. Network Critical builds diode capability into existing SmartNA-PortPlus and SmartNA-XL hardware. Historian export can ride on infrastructure your team already deploys for broader traffic monitoring. It is backed by perpetual licensing, not a subscription model. Drag-n-Vu keeps configuration inside a graphical interface. OT teams can complete deployment without specialist network engineering support.

Talk to the Network Critical team to walk through your historian export requirements. Confirm which deployment model fits your OT segmentation plan.