Hirschmann RH1-TP/FL Retrofit-Compatible Ethernet Hub

Hirschmann RH1-TP/FL Retrofit-Compatible Ethernet Hub: Seamless Legacy System Upgrade

The Hirschmann RH1-TP/FL is a ruggedized, rail-mounted Ethernet hub engineered for demanding industrial environments where network continuity and backward compatibility are non-negotiable. As automation engineers face the growing challenge of modernizing aging control architectures — from early-generation PROFIBUS-linked PLCs to legacy SCADA panels — the RH1-TP/FL serves as a reliable, drop-in network node that bridges older 10BASE-T copper segments with contemporary control infrastructure. Whether you are upgrading a control cabinet in a petrochemical plant, retrofitting a conveyor line in a food processing facility, or extending network reach inside a switchgear enclosure, this hub delivers the port density, environmental tolerance, and installation flexibility that legacy retrofit projects demand.

The RH1-TP/FL supports both TP (twisted-pair) and FL (fiber link) interfaces, making it particularly valuable in mixed-media environments where copper runs terminate at a junction box while fiber carries the signal across longer distances or electrically noisy zones. This dual-interface capability eliminates the need for separate media converters in many retrofit scenarios, reducing component count, simplifying wiring, and shortening commissioning time. Engineers replacing end-of-life hubs from discontinued product lines — including earlier Hirschmann MICE, RS2, and SPIDER series devices — will find the RH1-TP/FL a practical interim or permanent solution depending on the scope of the modernization roadmap.

Before integrating the RH1-TP/FL into an existing control cabinet, retrofit planners should verify several critical parameters. Power supply compatibility is the first checkpoint: the hub operates on a 24 VDC rail, and the existing PSU — often a Phoenix Contact QUINT or TRIO series unit — must have sufficient residual capacity after accounting for all connected modules. Terminal wiring should be confirmed against the original hub’s pinout; while the RH1-TP/FL uses standard screw-terminal blocks, older installations may have used ferrule-crimped conductors sized for a different current rating. Backplane interface and DIN-rail footprint must also be measured, as control cabinet real estate is frequently constrained in legacy panels that were designed decades ago with no provision for future expansion.

Module addressing is not applicable to an unmanaged hub, but if the RH1-TP/FL is being deployed alongside a managed switch — such as a Hirschmann RS20 or MACH100 series device — VLAN and port assignment configurations in the managed switch must be reviewed to ensure the hub’s connected devices are placed in the correct broadcast domain. Program logic compatibility in the upstream PLC (commonly a Siemens S7-300, S7-400, or Allen-Bradley ControlLogix platform) is unaffected by the hub itself, but any IP address changes resulting from network restructuring must be reflected in the PLC’s Ethernet communication function blocks before the system is brought back online.

Upgrade Compatibility Table

Retrofit Planning for Existing Automation Systems

A successful retrofit begins well before the maintenance window opens. When the RH1-TP/FL is being introduced into a legacy control network, the surrounding ecosystem of components must be audited in parallel. The upstream managed switch — frequently a Hirschmann RS20-1600T or a MACH104 series device — should have its firmware version noted, as older firmware may not correctly handle the hub’s collision domain behavior in half-duplex segments. The power distribution rail feeding the hub should be traced back to the primary 24 VDC bus, and any inline fuse holders or circuit breakers should be rated appropriately for the added load.

On the field device side, the RH1-TP/FL typically connects to remote I/O stations, operator panels, or drive controllers. In a Siemens ET 200S or ET 200M distributed I/O configuration, the Ethernet segment served by the hub carries PROFINET frames, and the interface module — such as an IM 151-3 PN — must be confirmed to operate at 10 Mbps if the hub does not support auto-negotiation. Similarly, if a Siemens TP700 Comfort or TP900 Comfort HMI panel is connected through this hub, the HMI project’s network adapter settings should be reviewed to ensure the IP address and subnet mask are consistent with the restructured network topology.

For installations where the RH1-TP/FL replaces a failed or end-of-life hub in a fiber ring, the fiber patch cords connecting to adjacent nodes — whether those nodes are Hirschmann SPIDER5 units or RS2-FX/FX switches — must be inspected for connector cleanliness and bend radius compliance. A dirty SC connector is one of the most common causes of intermittent link loss after a hub replacement, and a simple fiber inspection scope check before closing the cabinet door can prevent hours of troubleshooting later. Signal isolators on analog I/O channels feeding the same control cabinet should also be verified, as ground loop issues sometimes surface after network hardware changes disturb the cabinet’s grounding topology.

Programming cable access is another practical consideration. If the PLC in the same cabinet requires a firmware update or program modification as part of the broader upgrade, ensure that the programming cable — typically a Siemens PC Adapter USB or a Profibus MPI cable — is available on-site before the maintenance window begins. Downloading a revised program after the network is restructured is far more efficient than discovering a compatibility issue after the system has been partially recommissioned.

Downtime Control During System Migration

Minimizing production downtime during a hub replacement is achievable with disciplined pre-staging. The RH1-TP/FL should be pre-wired on a temporary DIN rail section in the workshop, with all cable labels transferred from the original hub’s wiring diagram. Power and signal connections should be verified on the bench using a portable 24 VDC supply before the unit is transported to the installation site. This bench pre-test, combined with a fiber loopback check on the FL port, eliminates the most common failure modes before the cabinet is even opened.

During the actual swap, the original PLC program should be backed up to a memory card or laptop before any hardware is disturbed. If the control system uses a Siemens S7-300 with a CP 343-1 Ethernet communication processor, the CP module’s configuration should be exported from STEP 7 or TIA Portal so that it can be restored quickly if the network restructuring causes any communication faults. The same principle applies to Allen-Bradley systems: export the RSLogix 5000 or Studio 5000 project file and note the current Ethernet/IP scanner configuration before disconnecting any cables.

Once the RH1-TP/FL is installed and powered, the commissioning sequence should follow a structured approach: verify 24 VDC supply voltage at the hub’s terminal block, confirm the PWR LED illuminates, then connect devices one port at a time while monitoring the link LEDs. This incremental approach isolates any cabling faults to a specific port rather than presenting a confusing all-ports-down scenario. The total expected downtime for a straightforward hub replacement using this methodology is typically under 30 minutes, even in complex multi-drop configurations.

Field control continuity can be further protected by pre-configuring a spare RH1-TP/FL unit as a hot standby, stored in the control room. Given the hub’s compact DIN-rail form factor and the availability of stock from NINERMAS, maintaining one spare unit per critical production line is a cost-effective insurance policy against unplanned outages caused by hub failure.

Retrofit Support FAQ

Q: Is the Hirschmann RH1-TP/FL a direct replacement for the discontinued RH1-TP/FL-EEC variant?
A: The RH1-TP/FL is functionally equivalent to the EEC (Extended Environmental Class) variant in most retrofit applications. Both share the same interface configuration and DIN-rail footprint. However, customers should confirm the operating temperature range against their specific site conditions, as the EEC designation indicates an extended cold-start rating that may be relevant in unheated outdoor enclosures.

Q: Can the RH1-TP/FL be used in a PROFINET network alongside managed switches?
A: Yes, with an important caveat. The RH1-TP/FL is an unmanaged hub operating at 10 Mbps in half-duplex mode. When connected to a PROFINET segment, it introduces a shared collision domain for all attached devices. For time-critical PROFINET IO applications with short update cycles, a managed switch with full-duplex ports is strongly recommended. The RH1-TP/FL is best suited for non-time-critical device connections or legacy 10BASE-T segments where a managed switch is not justified.

Q: What pre-shipment testing is performed on each unit?
A: Every RH1-TP/FL unit supplied by NINERMAS undergoes functional power-on testing, port link verification on all TP and FL interfaces, and visual inspection for physical damage before dispatch. Units are shipped with original or equivalent packaging to prevent transit damage. A 12-month warranty covers all units from the date of shipment, including dead-on-arrival replacement at no additional cost.

Q: What is the typical lead time and stock availability?
A: NINERMAS maintains inventory of the RH1-TP/FL to support urgent retrofit and breakdown replacement requirements. Standard orders are dispatched within 1–3 business days. For large-quantity orders or scheduled maintenance projects, contact our sales team in advance to confirm allocation. Customers are encouraged to maintain at least one spare unit per critical installation to eliminate lead time risk during unplanned outages.