Yokogawa AAP135-S50 Pulse Input Module CENTUM VP 8-Channel

Product Overview

The AAP135-S50 (AAP135) is a high-precision, 8-channel isolated pulse input module designed for the Yokogawa CENTUM VP distributed control system (DCS). This module is engineered to interface with field devices providing contact ON/OFF, voltage pulse, or current pulse signals, supporting an input frequency range from 0 to 10 kHz. Ideal for flow metering, turbine speed monitoring, and totalizing applications in power plants and chemical processing facilities, the AAP135 ensures maximum signal integrity through comprehensive channel-to-channel isolation. Its architecture supports dual-redundant configurations, allowing for seamless failover in mission-critical loops. By utilizing a 2 ms data update period and integrated chatter elimination filters, the module provides the rapid, clean data acquisition necessary to reduce system latency and minimize process downtime.

Suffix Breakdown

The AAP135-S50 model number follows Yokogawa's structured nomenclature to define its hardware grade and certification level:

• -S: Designates the Standard type module for general-purpose industrial control applications.

• 5: Indicates the hardware is configured with no explosion protection, suitable for safe-area installation or within purged cabinets.

• 0: Specifies the Basic type configuration, providing standard pulse counting and status input functionality without additional specialized hardware modifiers.

Technical Specifications

Technical FAQs

What types of field signals can the AAP135-S50 process?

The module is highly versatile, supporting 2-wire configurations for contact ON/OFF, voltage pulses, and current pulses (with transmitter power supply available), as well as 3-wire power-supply-type voltage pulses.

How does the module handle mechanical relay "chattering"?

The AAP135 includes a configurable digital filter designed to eliminate signal noise and chattering. When the pulse input is a dry contact (mechanical relay) at frequencies up to 10 Hz, this filter prevents false pulse counts.

What is the benefit of channel-to-channel isolation?

Unlike group-isolated modules, the AAP135 is isolated between each individual channel and the system. This prevents ground loops and ensures that a surge or fault on one field instrument does not propagate to or affect the readings of the other seven channels.

Engineering & Installation Guide

• Mounting and Clearance: The module dimensions are 32.8 mm in width and 130 mm in height. When installing in a CENTUM VP node unit, ensure that the module is fully seated into the backplane connector and the fixings are hand-tightened. Maintain sufficient cabinet airflow to keep the ambient temperature within the -20 to 70 deg C range, especially in high-density I/O configurations.

• Wiring for High Frequency: For pulse signals approaching the 10 kHz limit, use high-quality twisted, shielded pair cabling. The shield should be grounded at the system end only to mitigate electromagnetic interference. The maximum signal source resistance should be kept at 1 kOhm or less to ensure clear voltage swing (VH-VL) detection.

• Transmitter Power Supply: The module can select between 24 V DC and 12 V DC for transmitter power. Note the current limiter values: 30 mA for 24 V and 40 mA for 12 V. Exceeding these limits will trigger internal protection circuits and may result in intermittent signal loss.

• Redundancy Planning: If deploying in a dual-redundant configuration, ensure the shunt resistance is set to "none" on the standby side to maintain high impedance. The module automatically manages shunt activation during a failover event.