Application Scenarios
On a 2050 mm hot-strip roughing stand in a Northeast Asian integrated mill, the SIMADYN D PM6 rack still owns the hydraulic AGC loop because the re-engineering cost to TDC/S7-1500 + TM54F was quoted at seven figures and a 14-day downtime the mill couldn’t give. The 6DD1606-4AB0 on that PM6 carries the real-time signal load: 4 × V/F integrating inputs hooked to the two backup tacho generators and two encoder channels (V/F conversion means the PM6 firmware accumulates pulses over the scan and derives RPM with 16-bit resolution — something a standard ±10 V A/D card can’t do without external F/V). The 4 × A/D channels take the two hydraulic-cylinder LVDTs and two screwdown load-cells; 16 BO drive the servo-valve enable relays and the HAGC “inhibit” tree; 16 BI pick up the screwdown limit switches, hydraulic pump running OK, and lube-fault contacts. When one 6DD1606-4AB0 started throwing sporadic A/D channel-3 CRC errors after 22 years (the Ni-Au edge connector oxidized), maintenance pulled the card, sprayed DeoxIT, reseated — but ordered two more 6DD1606-4AB0 spares the same afternoon. Downtime: 12 minutes. The alternative — ripping the PM6 + IT42 combo for a TDC/S7-1500 migration — was a 10-day outage. That’s the IT42’s enduring raison d’être.
Parameters
| Main Parameters | Value / Description |
|---|---|
| Product Model | 6DD1606-4AB0 |
| Manufacturer | Siemens (SIMADIC D family) |
| Product Category | I/O Submodule – plugs onto PM4 / PM5 / PM6 processor baseboard |
| Digital Inputs | 16 BI (binary inputs), 24 V DC sink/source via SB/SU interface modules |
| Digital Outputs | 16 BO (binary outputs), 50 mA driver per channel, via SB/SU |
| Analog Inputs (A/D) | 4 ch, 12-bit ADU, ±10 V / ±20 mA / 0–20 mA (via SC51 + SU10 interface) |
| Analog Inputs (V/F) | 4 ch, integrating UFC (voltage/frequency conversion) – for tacho/encoder; 16-bit counter depth, external trigger inputs |
| Analog Outputs | 4 ch, 12-bit D/A, ±10 V / 0–20 mA, Latch + Driver |
| Bus Interface | Local expansion bus to PM baseboard; dual-port RAM to PM CPU |
| Electrical Isolation | 2.5 kV (channel ↔ logic ground) |
| Max ITxx per PM | 2 (IT42 counts as 1 slot on top of the PM’s own mounting slot) |
| Op. Temperature | -20 … +60 °C (storage -40 … +85 °C) |
| Dimensions (L×W×H) | 279 × 274 × 48 mm (Siemens packaging dims; module PCB footprint smaller, mounts in SIMADYN D rack) |
| Weight | 0.597 kg (net) |
| Mounting | Plug-on to PM4/PM5/PM6 CPU baseboard in SIMADYN D cabinet |
| Lifecycle | PM500 Discontinued – deleted without replacement (effective 2017-10-01) |
| Certifications | CE, UL, CSA (per SIMADYN D family) |
Technical Principles and Innovative Values
- Innovation Point 1 – V/F integrating AIN is the IT42’s secret weapon. Standard A/D cards sample voltage. The 6DD1606-4AB0‘s 4 × V/F channels use UFC (voltage/frequency converter) blocks feeding 16-bit counters on the IT42 controller — meaning a 0–10 V tacho or encoder signal gets integrated over the PM scan, giving high-resolution RPM even at low shaft speeds. For a roughing-stand main motor doing 20–80 rpm, that’s the difference between usable AGC and a jittery loop. No ET 200 card does this natively.
- Innovation Point 2 – Local expansion bus, not backplane PROFIBUS. The 6DD1606-4AB0 doesn’t travel over DP; it hangs off the PM4/PM5/PM6 baseboard’s local expansion bus into a dual-port RAM that the PM CPU polls at the drive-task rate (sub-ms). The AGC torque-demand → valve-output loop stays inside one PM scan — essential when the hydraulic cylinder has a ~30 Hz bandwidth and the screw has ~5 Hz. An S7-400 + ET 200 + PROFIBUS DP @ 12 Mbps would add 2–3 ms of jitter that the AGC loop would notice.
- Innovation Point 3 – Mixed-signal density on one subcard. 16 BI + 16 BO + 8 AI + 4 AO on a single 6DD1606-4AB0 was—and still is—densely packed for 1998-era tech. The PM baseboard itself only carries the CPU + COM5/COM7 fiber links; all field I/O funnels through 1–2 IT42s and maybe an IT41 (lower-density sibling). That keeps the PM slot count tight in a 19″ SIMADYN D rack.
- Innovation Point 4 – Interface-module decoupling. The 6DD1606-4AB0 itself doesn’t land field wires — the 96-pin DIN connectors (X6/X7/X8) go to interface modules SB10/SB60/SB70/SU10/SC50/SC51 that do level shifting (230 V→24 V, 48 V→24 V), relay galv-separation, or straight 1:1. That means one 6DD1606-4AB0 can serve a 230 V AC binary plant or a 24 V DC binary plant just by swapping SB modules — the IT42 never changes.
- Innovation Point 5 – 2.5 kV channel isolation + -20…+60 °C. The 6DD1606-4AB0 was specced for converter-hall environments (cycloconverters throw kV-level dV/dt) — 2.5 kV ISO between field channels and the PM’s 5 V logic, and 60 °C max because SIMADYN D cabinets in cement/steel sit hot. Twenty-five years on, the ISO is usually the last thing to fail; the edge-connector gold fingers go first.
