HIMA F3236 16-Fold Safety Input Module: Where Field Signals Meet Safety Logic
In the architecture of a Safety Instrumented System, the boundary between the physical world and the logic solver is guarded by modules that must ever fail silently. The HIMA F3236 is one such gatekeeper — a 16-channel digital input module designed to acquire safety-related signals from emergency stops, pressure switches, valve position feedback, and other critical field devices, and pass them into the HIMA safety controller with a level of integrity that meets the highest functional safety requirements.
Analog input module X-AI 32 01 32 channels, 4 ... 20 mA, line monitoring, SIL 3
Analog input module X-AI 32 02 32 channels, 4 ... 20 mA, line monitoring, SOE, SIL 3
Analog input module X-AI 32 51 32 channels, 04 ... 20 mA, line monitoring
Counter module X-CI 24 01 24 channels, 0 ... 20 kHz, SIL 3
Counter module X-CI 24 51 24 channels, 0 ... 20 kHz
Output modules
Digital output module X-DO 32 01 32 channels, 24 VDC, 0,5 A, short-circuit monitoring LS, individual channel shut-off, SIL 3
Digital output module X-DO 32 51 32 channels, 24 VDC, 0,5 A, protected outputs, group shut-off
Digital output module X-DO 24 01 24 channels, 24 VDC, 0,5 A, line monitoring LSLB, individual channel shut-off, SIL 3
Built for Safety Isolation, Not Just Signal Acquisition
The F3236 is specified for use with 1-signals or sensors that carry a safety isolation requirement class AK That designation is not incidental — it reflects the module's role in systems where a failure to detect a signal, or a failure that produces a false signal, could compromise a safety function.
The module accepts two input types: a . This dual-mode capability allows the same module to interface with both active current-loop sensors and passive dry contacts, giving panel designers flexibility without sacrificing safety certification.
The Self-Test Philosophy
What distinguishes the F3236 from ordinary digital input cards is its approach to diagnostics. The module performs automatic full testing during operation — not as a periodic maintenance routine, but as a continuous background function.
The essential test procedures include three distinct checks:
Cross-talking of the inputs using a walking-zero pattern — a technique that verifies channel isolation by sequentially injecting test conditions that would reveal signal leakage between adjacent inputs
Function of the filter capacitors — validating the integrity of the input conditioning circuitry
Overall module function — a comprehensive self-check of the card's operational health
This continuous self-testing means the module does not merely detect faults after they have occurred; it actively works to identify latent failures before they can compromise a safety loop.
Technical Specifications
Inputs | 16 channels |
Input Signal | 1-signal, 6 mA (incl. cable plug) or mechanical contact 24 V |
Switching Time | Typical 8 ms |
Space Requirement | 4 TE (standard Eurocard width) |
Operating Voltage | 5 V DC: 120 mA / 24 V DC: 200 mA |
Safety Requirement Class | AK 1 to AK 6 |
Physical Interface and Wiring
The F3236 connects to field devices through a front-mounted cable plug, with the mating cable specified as LiYY 16 × 0.25 mm² with a length of 750 mm. The cable plug carries 16 individual channel leads, each color-coded for identification: channel 1 is white (ws), channel 2 is brown (br), channel 3 is green (gn), and so on through channel 16 at white-blue (ws-bl).
The cable also includes dedicated conductors for power and screening: L− (z2, black sw) and L+ (z12, red rt) for the 24 V supply, and a screen connection (z4, z6, yellow-green) that terminates via a flat pin plug to the earth bar beneath the module slot. This shielding arrangement is critical for rejecting electromagnetic interference in industrial environments where the module may be installed alongside variable frequency drives, contactors, and other noise-generating equipment.
Application Context
The F3236 is deployed where discrete safety signals must be acquired with certified integrity — Emergency Shutdown systems in petrochemical plants, burner management systems in power generation, fire and gas detection loops on offshore installations, and process interlock circuits in chemical manufacturing. In these applications, the module's ability to distinguish between a genuine process trip and a spurious signal caused by electrical noise or wiring fault is not a convenience — it is a safety requirement.
