Product Overview
The HIMA 42300 is a Logic Function Module from HIMA, the German safety automation specialist whose hardware protects emergency shutdown systems, burner management systems and high-integrity pressure protection systems in process plants worldwide. The HIMA 42300 belongs to the Planar4 family, HIMA’s hardwired safety concept in which every module integrates input conditioning, logic processing and output driving on a single board, and in which the safety logic is created by physical wiring rather than by a downloaded software program. This distinction is the whole point of the platform: the safety function exists in copper and silicon, not in code, so there is no compiler, no firmware revision and no scan cycle standing between a dangerous process condition and the trip that stops it.
The function performed by the HIMA 42300 is deliberately narrow and deliberately simple. It provides eight independent OR elements, each accepting two inputs, so that any one of a pair of safety signals can energise the corresponding output channel. In practice this is the function that safety systems need most often: combining two independent trip causes into one shutdown demand, or gathering multiple detector contacts into a single alarm or trip output. Because the logic is implemented as a redundant diode matrix with a high reverse-blocking capability, the eight channels behave identically and independently, and a fault on one element cannot propagate into its neighbours.
Within the automation hierarchy, the HIMA 42300 sits inside the safety instrumented system itself, alongside input, output, relay, timer and other logic function modules, forming the hardwired decision layer between field sensors and final elements. Certified for use up to SIL 4 under IEC 61508 within the Planar4 architecture, and built as a 3 U, 4 SU Eurocard for DIN rail or dedicated rack mounting, it is the kind of component that engineers specify when the safety function must be provable by inspection rather than by software validation.
Technical Specifications
| Parameter Name | Parameter Value |
|---|---|
| Product Model | HIMA 42300 (Logic Function Module, order number 42300) |
| Manufacturer | HIMA Paul Hildebrandt GmbH, Germany |
| Product Type | Logic Function Module / 8-Channel OR Element |
| System Platform | HIMA Planar4 hardwired safety system (logic realised by wiring, no software programming) |
| Logic Function | OR (logical OR) element; output energised when either input is active |
| Number of Functions | 8 independent OR elements per module |
| Inputs | 2 inputs per OR element, 16 inputs per module |
| System and Supply Voltage | 24 V DC (Planar4 system supply) |
| Current Consumption | Approximately 10 mA module consumption; approximately 20 mA input current |
| Output Stage | Redundant diode matrix with high reverse-blocking capability |
| Output Ratings | Reverse voltage 1000 V; reverse current limited to 50 mA; peak on-state voltage 3 V; nominal on-state current max. 200 mA |
| Reverse Recovery Time | 30 ms typical |
| Channel Protection | 0.375 A time-delay fuse per channel |
| Safety Integrity | SIL 4 within the Planar4 architecture to IEC 61508; designed in accordance with DIN V 19250 principles |
| Diagnostics | Module status indication, dedicated fault output and a relay contact that opens on fault for safe-state annunciation to the process control system |
| Hardware Format | Eurocard, 3 U height, 4 SU width; DIN rail or dedicated rack mounting |
| Dimensions (W × H × D) | Approximately 3.2 × 21 × 13.3 cm |
| Weight | Approximately 0.12–0.2 kg |
Main Features and Advantages
Eight independent OR elements in one Eurocard: The HIMA 42300 delivers eight completely separate 2-input OR functions in a single module, which is the configuration most safety matrices actually need — two trip causes per shutdown output, two detector contacts per alarm group, two permissive conditions per start circuit. Consolidating eight elements into one board reduces panel space, wiring and termination errors, while keeping each channel electrically independent so that no single element can influence another.
Hardwired determinism instead of software scanning: Because the HIMA 42300 implements logic in hardware, its response is not subject to a controller scan cycle, a task scheduler or an operating system. The output follows the input in microseconds, consistently, every time. For the extremely time-critical safety circuits where Planar4 is specified — overpressure protection, compressor and pump trips, main shutdown systems — that determinism removes an entire category of timing uncertainty from the safety case, and it removes the software validation and change-management burden that programmable safety controllers impose.
Robust output stage engineered for industrial reality: The redundant diode structure of the HIMA 42300 withstands 1000 V reverse voltage with reverse current limited to 50 mA, a peak on-state voltage of 3 V and a nominal on-state current up to 200 mA, and each channel is protected by its own 0.375 A time-delay fuse. The practical benefit is resilience: wiring mistakes, induced transients and load faults that would destroy a lighter module are absorbed, and the fuse discrimination means a single channel fault is isolated rather than taking the module offline.
Built-in fault visibility: The HIMA 42300 provides module status indication together with a dedicated fault output and a relay contact that opens when a fault is detected. This lets the safety system report its own health to the process control system or to an annunciator panel, so that a degraded module is identified and replaced during a planned window rather than discovered during a demand on the system.
Compact, service-friendly hardware: At roughly 3.2 × 21 × 13.3 cm and under 0.2 kg, the HIMA 42300 fits dense safety cabinets, and the DIN rail or rack format means a spare can be swapped in minutes with ordinary tools. For plants running legac
