TRICONEX 3511 Pulse Input Module

Design Positioning

The 3511 is the only “low-speed” pulse-input card in the Tricon fault-tolerant family.
Instead of racing for high bandwidth, it stretches the sampling window to 167 µs-class and concentrates on frequencies from 0 – 3 kHz coming from slow magnetic pick-ups and dry contacts. Typical targets include:

ü Extruder screw speed

ü Metering-pump stroke counting

ü Belt feeder speed feedback

ü Low-speed agitator blade monitoring

 Hard-difference Matrix vs. 3510 & 3515

Wiring & Noise Hints

1. Use shielded twisted-pair ≤300 m, shield earthed at 3511 end only.

2. For dry contacts or NAMUR sensors add external 2 kΩ pull-up to 24 V to obtain ≥2 mA wetting current.

3. With 2-wire mag pick-ups short “–” to 3511 COM; the on-board 3.9 kΩ terminator supplies auto-bias.

4. 250 V rms common-mode is allowed between channels, so 24 V and 48 V sensors can be mixed without external isolators.

 Functional Highlights

1. Zero-speed alarm: if period >20 s a “Zero-Speed” bit is set—ideal for stall interlocks.

2. Frequency-to-current conversion: on-board algorithm converts Hz into 0 – 100 % floating point, saving one AO module.

3. Accumulator snapshot: read 24-bit totalizer via SOE with ±1 pulse accuracy—suitable for custody-transfer.

4. Phase-difference detect: dual-channel quadrature mode calculates direction, helpful for bucket-elevator slip monitoring.

What happens next?