What to check before you order
- Two CPUs in hot standby, memory mirrored, a bumpless switchover, and one logic project, so the maintenance team is not keeping two programs.
- Redundant power and two network paths, for continuous petrochemical and metals lines that have a high-availability target.
- Rack I/O and communication modules expand in a way that fits a layered DCS or PLC.
- SimtoLink can supply a switchover test script and a yearly drill checklist.
A rack for a line that does not stop
Built for a process main that cannot be shut down. A failed CPU, supply, or network path becomes a switchover you can plan, so the maintenance window can stay long and the line stays running.
SimtoLink supplies the sync-link wiring, the fiber and copper length limits, and a two-version firmware rollback. Volume jobs can split redundancy domains across racks with remote I/O.
How the pair stays in step
IEC 61000-4 level 4 items are on the record. Ports have surge and reverse-polarity protection. Ground is zoned so a loop or common-mode noise is less likely to split the pair. Outdoor and coastal orders can take a higher ingress rating and a corrosion coating.
Parameters and thresholds load as a batch. Selected models store an event or a waveform. OTA carries settings and firmware. Accept the rack with a power-on self-test, a time sync, and a sample of points. For metering or safety, SimtoLink helps with a third-party metrology submission and the type-test file.
Hardware figures
Typical order, for selection and for a bid clause. For a wider range, a redundant supply, or an intrinsically safe explosion-proof variant, ask SimtoLink for the hardware specification and the installation guide. Order codes can differ slightly; the nameplate and the papers in the box decide.
| Item | Specification | Note |
|---|---|---|
| I/O | 1024 points | Distributed expansion |
| Scan cycle | 3.8 ms | Instruction-level |
| Programming | CODESYS | Online debug |
| Communication | Modbus TCP | Dual port |
| Redundancy | CPU hot standby | Bumpless switchover |
| Safety | Standard | TÜV |
| Storage | Program 8 MB | Holds through a power loss |
| Operating temperature | -21～59 ℃ | Wide temperature range |
| Supply | AC 220V | Surge 4kV |
| Certification | CE | Industry compliance |
Lines that cannot stop
Three plants where the switchover is proved before the rack is left in charge.
Continuous petrochemical units
The reaction and separation master runs hot standby, and SIL loops sit in their own zones.
Metals and rolling
On a seconds-scale cycle the switchover is bumpless, so steel does not pile and the line does not trip.
Energy and site utilities
Boiler, compressed-air, and circulating-water masters stay up, so the site keeps steam and compressed air.
Install, ground, and recheck
- Confirm the supply window and polarity before the rack is powered. Measure the bus and the breaker if the feed is uncertain.
- Shielded twisted pair for the network, shield at one end, kept off long power-cable runs.
- In the lab, read and write both ways and trip one threshold against the host, then move the rack.
- If any part is outdoors, let water leave and air move, look at the seal, and keep the lightning earth inside the local rule.
- Every 24 months, sample a set of points and archive the log.
Order, documents, and support
SimtoLink supplies the hardware specification, the outline, a wiring table, and a sample project. Volume orders can include a sample review and a factory inspection. Warranty and calibration follow the contract and the papers in the box.
Related control hardware
High availability and safety, next to this rack: