Allen Bradley (Rockwell) Standardized Function Blocks: Ensuring Consistency in Water and Wastewater Automation

[Erkan Teskancan]

In water and wastewater automation, standardization with reusable function blocks is both technically feasible and economically advantageous.

### The Problem of Inconsistency in Automation
Code inconsistency in different automation systems used in municipal water and wastewater facilities is a serious problem. The use of multiple platforms such as Emerson PACSystems, Rockwell ControlLogix, and Micro800 leads to custom programming at each facility, increasing maintenance and operational issues. For example, while engineering time for a similar pump station ranges from 35-40 hours, this situation drives up costs across hundreds of facilities.

### Solution: Multi-Platform Function Block Library
A comprehensive library of reusable function blocks has been developed that operates functionally consistently across three different PLC platforms (Rockwell ControlLogix/CompactLogix, Rockwell Micro800, Emerson PACSystems RX3i).

### Core Function Blocks

• Advanced motor/pump control; VFD integration, runtime tracking, and predictive maintenance.
• Intelligent valve control; position verification and travel time monitoring.
• Analog signal optimization; measurement, aggregation, and prioritized alarm management.
• Pump rotation sequencer; automatic lead-lag rotation and runtime equalization for up to 10 pumps.

### Design Approach
Cross-platform function blocks have been optimized based on functional equivalence. Functionality was prioritized over code identity, and they were designed to allow technicians to perform configuration. Each block includes a simulation feature, enabling testing and acceptance procedures without physical equipment.

### Tangible Benefits

• Engineering time decreased by 85% per motor, valve, or analog point, down to approximately 30 minutes.
• Over 1200 hours of programming time saved.
• Commissioning errors reduced from 15-20 to 2-3 per project.
• Intervention times decreased from 4 hours to 30-60 minutes.
• Code similarity increased from 30% to 95%.
• Operators adapted 40% faster between different facilities.

### Adoptability for the Industry
The ability of function blocks to operate on multiple PLC platforms, along with their scalable and customizable structure, adds flexibility to standardization efforts. It provides an easy-to-implement framework for engineering firms, facilities, and system integrators.

### Case Study
In a wastewater treatment plant upgrade project with an eight million gallons/day capacity, programming, which traditionally took 140 hours, was reduced to 24.5 hours thanks to function blocks; testing, commissioning, and training times were significantly decreased.

### Future Outlook
The function block library is being updated with features such as cybersecurity, cloud connectivity, advanced diagnostics, and energy optimization. Its widespread adoption as an industry standard will reduce engineering costs, increase reliability, and facilitate knowledge transfer.

This example demonstrates that standardization in water and wastewater automation is technically and economically viable. For businesses experiencing code inconsistency issues, reusable function blocks are a valuable solution that warrants investment.