Invensys Triconex 3515 Pulse Totalizer Input (PTI) Module

TRICONEX 3515 Pulse Totalizer Input (PTI) Module

The TRICONEX 3515 is a 32-point pulse totalizer input module with Triple Modular Redundancy (TMR) architecture. It provides 32 independent 31-bit counters for measuring pulse quantities from flow sensors, turbine meters, and per-unit sensors. Each counter operates independently and can be reset individually or in bulk by the control program, making it ideal for batch processing and flow totalization applications.

• Type: TMR Pulse Totalizer Input (PTI)
• Input Points: 32, non-commoned
• Input Frequency Range: 0 Hz to 1 kHz
• Minimum Pulse Width: 300 microseconds
• Maximum Count: 2,147,483,647 (2³¹ − 1)
• Counter Overflow: 596 hours (24 days) at 1 kHz worst case; count wraps to negative integer
• Count Up Switching: Rising edge (OFF to ON)
• Switching Voltages: OFF→ON: 15 VDC typical (18 VDC worst case); ON→OFF: 8 VDC typical (6 VDC worst case)
• Typical Hysteresis: 4 VDC
• Normal Turn-On Current: 6–9 mA
• Count Input Delay: < 15 ms
• Point Isolation: 1,500 VDC minimum (opto-isolated)
• Accuracy: ±2 counts (active module)
• Logic Power: < 10 watts
• Field Power Load: 0.5 W per ON point; 1.5 W at maximum field voltage
• Diagnostic Indicators: ON/OFF state per point; PASS / FAULT / ACTIVE module status
• Color Code: Purple
• Hot-Spare Support: Yes (re-educates counter values from active module)

Installation Guide

1. Install the 3515 into an I/O slot in the Tricon chassis. Ensure mechanical keying aligns correctly.
2. Connect to a compatible termination panel (e.g., 9753-110 basic termination panel).
3. Wire pulse sources (flow meters, encoders) to the termination panel. Verify signal voltage levels (< 42.5 VDC absolute maximum).
4. Configure counter reset behavior in TriStation 1131. Set batch reset logic to clear counters before each batch to prevent overflow.
5. Monitor diagnostic indicators. A FAULT light indicates a channel diagnostic failure (not necessarily a module failure).

FAQ

Q: What happens when a counter overflows?
A: The count wraps to a negative integer. At 1 kHz continuous input, overflow occurs after approximately 24 days. Design your control program to reset counters before batch operations.

Q: Can I hot-swap a 3515 module?
A: Yes. The 3515 supports hot-spare operation. When replacing an active module, the hot-spare re-educates all counter values to maintain continuity.

Q: What is the difference between 3515 and 3511?
A: The 3515 is a pulse totalizer (accumulates counts over time). The 3511 is a pulse input module (measures frequency, 20–20,000 Hz, 8 points). Choose 3515 for flow totalization/batching; choose 3511 for speed/frequency monitoring.

Selection Tips

• Use 3515 for batch processing, flow totalization, and quantity measurement applications in oil & gas and chemical industries.
• Ensure pulse source output voltage exceeds 15 VDC (typical turn-on) for reliable counting.
• For high-frequency applications (> 1 kHz), consider alternative signal conditioning or the 3511 pulse input module.
• Pair with 9753-110 termination panel. Verify panel compatibility in the Tricon Technical Product Guide.