Description
The Siemens 6DD2920-0AR5 is the Synchronization Module within the SIMADYN D digital control system—a rack-mounted interface board that delivers inter-rack high-speed fiber communication and clock synchronization across distributed SIMADYN D processor racks (PM4/PM5/PM6, T400, FM458). Equipped with two fiber ports (POF 2 mm / GOF), the 6DD2920-0AR5 exchanges real-time process data and distributes the system clock at 12–25 Mbps with sub-microsecond jitter (< 1 µs), making it the backbone of multi-rack drive systems where a 100 µs clock skew between the roughing-stand rack and the finishing-stand rack would trash strip tension. The module ships complete with the SITOR SA60.1 transformer and the TRAFOBGR 6DD2920-0AR1 sub-assembly pre-integrated, weighs ~1.55 kg (the transformer accounts for the heft vs. a bare submodule), and draws 5 V DC from the SIMADYN D backplane. As with the broader SIMADYN D family, Siemens placed this into PM500 “Discontinued – Deleted Without Replacement” status, so verified NOS and tested-pulled units are the only supply path for live mills and power-plant turbine controls still on SIMADYN D.
Application Scenarios
On a Brazilian 6-stand hot-strip finishing train, the looper + inter-stand tension control is split across two SIMADYN D racks: Rack A (stands F1–F3, PM5 + two T400s) sits at the operator pulpit end, Rack B (stands F4–F6, PM6 + three T400s) sits 62 meters downstream near the coil-down-coiler entry. Originally the two racks talked over a PROFIBUS DP cross-link, but at 12 Mbit/s the 62 m copper run picked up EMI from the 6RA70 field supplies every time a stand accelerated—manifesting as sporadic “sync loss” faults that dropped the whole train once every 120–180 hours, costing ~$14k per trip. The retrofit installed a 6DD2920-0AR5 in each rack, linked via 100 m of POF (plastic optical fiber) through the existing cable tray. The fiber is immune to the 6RA70 switching noise, the 6DD2920-0AR5 locked clocks with < 0.8 µs jitter measured on the T400 encoder pre-processing, and the “sync loss” fault vanished completely. Eighteen months on, the mill added a third rack (F7 retrofit) and daisy-chained it off the second 6DD2920-0AR5—the same 12–25 Mbps pipe absorbed the extra telegram load without re-cabling. For multi-rack SIMADYN D plants, the 6DD2920-0AR5 is the difference between “DP works most of the time” and “clocks never drift.”
Parameter
| Main Parameters | Value / Description |
|---|---|
| Product Model | 6DD2920-0AR5 |
| Manufacturer | Siemens (SIMADYN D family) |
| Product Category | Synchronization Module (Inter-Rack Fiber Sync) |
| Sync Interface | 2 × Fiber ports (POF 2 mm / GOF, configurable) |
| Transmission Rate | 12 – 25 Mbps (real-time, config-dependent) |
| Sync Precision | Jitter < 1 µs (clock distribution across racks) |
| Topology Support | Point-to-point, star, ring (redundant capable) |
| Onboard Transformer | SITOR SA60.1 (pre-installed) |
| Included Sub-Assembly | TRAFOBGR 6DD2920-0AR1 |
| Backplane Supply | 5 V DC (via SIMADYN D rack backplane), typ. < 5 W |
| Diagnostics / Net Detect | Compatible with 6DD2920-0AR6 (network detection sibling) |
| LED Indicators | Power / Com Activity / Fault / Sync Lock / Clock Lock |
| Weight | ~1.55 kg (transformer accounts for mass) |
| Operating Temp. | 0 … +60 °C |
| Mounting | Eurocard slot in SIMADYN D 19″ subrack |
| Lifecycle | PM500 Discontinued (deleted, no Siemens replacement) |
Technical Principles and Innovative Values
- Innovation Point 1: Fiber-Base Clock Distribution Across Racks. A single SIMADYN D rack keeps its PM4/PM5/PM6 + T400/FM458 in sync via the backplane, but once you span two racks 30–200 m apart (typical in long bay mills or hydro-turbine governor arrays), copper PROFIBUS jitter blows up. The 6DD2920-0AR5 puts a PLL-locked clock transmitter on one rack and a receiver on the other, distributing the master clock over POF/GOF at 12–25 Mbps. Result: all T400 encoder inputs across both racks share the same µs-grade timebase—critical for cross-rack tension loops and flying-shear handoffs.
- Innovation Point 2: SITOR SA60.1 + TRAFOBGR Pre-Integrated. Unlike a bare sync PCB, the 6DD2920-0AR5 ships with the SITOR SA60.1 isolation transformer and the TRAFOBGR 6DD2920-0AR1 bracket already mounted—this is the “heavy” part (1.55 kg vs. a few-hundred-gram memory submodule). The transformer isolates the fiber transceiver supply from the rack’s 5 V backplane noise, and the TRAFOBGR provides the mechanical mounting + EMC shielding. One SKU = one install-ready assembly, no loose transformer to torque down separately.
- Innovation Point 3: Topology Resilience for Ring Configs. The 6DD2920-0AR5 supports line, star, and ring topologies; in ring mode, if a forklift cuts the POF midway between Rack A and Rack B, the ring heals through the alternate path (assuming a third rack or a media converter). For plants where “one fiber cut = line stop” is unacceptable, this is the differentiator vs. point-to-point copper DP.
Application Cases and Industry Value
Case 1 – Hydro Turbine Governor Array (Norway, 2019). A run-of-river plant has three 85 MW Kaplan units, each with a SIMADYN D rack (PM5 + T400 for guide-vane + blade pitch). The original design had each rack autonomous, but during grid-frequency dip events the three units drifted apart by ~40 ms in guide-vane response, causing reactive-power oscillation on the 132 kV export. The retrofit added a 6DD2920-0AR5 to each rack, POF-ringed them, and designated Unit 1 as clock master. All three T400s now run off the same µs-grade clock; the cross-unit response spread dropped to < 2 ms, and the reactive oscillation disappeared. The plant kept the original D7-SYS code—only added the sync FBs and the 6DD2920-0AR5 hardware.
Case 2 – Sectional Paper Machine (Indonesia, 2021). A 22-drive sectional paper line (dryer section, 6SE70 + SIMADYN D PM6 master rack + PM5 slave rack 40 m away) suffered “section speed drift” during grade changes—the slave rack’s T400 lagged the master by 6–9 encoder counts (~3 ms at 1500 rpm) because the PROFIBUS DP cross-link couldn’t hold timing under the dryer-section steam-valve solenoid noise. Swapping to 6DD2920-0AR5 fiber sync between the two racks eliminated the drift; grade-change overshoot dropped from 4.2 % to 0.9 %, and broke rolls (from tension spikes) went from 2/month to zero over six months.