Summary

Distributed Control: UniStream PLCs Unify 28 Textile Chemicals Across Pipeline Networks

Resilient and scalable—distributed control built on 7 UniStream PLC + HMI controllers that deliver uninterrupted chemical preparation and distribution for global textile manufacturing Gildan Corporation. The distributed architecture covers the entire chemical lifecycle: raw material intake into eight large tanks, formulation of up to 28 textile chemicals including dyes and fabric finishers in three mixers, transferring products into storage, and distributing them via pipelines to end users with full traceability and remote monitoring—all engineered in a single Unitronics’ UniLogic software project

The Company

Gildan Corporation is a major vertically-integrated apparel manufacturer that operates advanced textile facilities throughout the Americas.

Gildan’s textile operations depend on an uninterrupted supply of precisely formulated chemicals delivered safely to production lines around the clock. 

To achieve this, Gildan partnered with automation engineer Ober Yela,  head of projects at Central de Mangueras in Honduras, to design a fully automated system for chemical preparation and distribution.

The Challenge: Complex, Continuous Chemical Supply

Gildan needed a system capable of managing a multi-stage process without downtime:

• Eight raw-material tanks, each up to 28,000 kg, with continuous level monitoring and isolation.
• Three mixers (2, 12, and 20 tons) running multiple recipes in parallel with precise dosing requirements.
• Transfer of 28 chemicals from mixers to storage tanks through a single shared pipeline, requiring strict automated flushing to prevent cross-contamination.
• High availability, even in the event of communication loss or hardware failure.
• Full traceability, with events—every receipt, dosing operation, transfer, and shipment—logged to SQL for compliance, cost allocation, and process optimization.

Real-time remote visibility for operators and management.

The Solution

Engineer Yela used seven Unitronics UniStream 10" PLC + HMI controllers to implement a distributed architecture that covers the entire chemical lifecycle: receiving raw materials into eight large tanks, preparing up to 28 textile chemicals in three mixers, transferring products into storage, and distributing them via pipelines to end users with full traceability and remote monitoring.

System Architecture: Three Integrated Tiers

Engineer Yela structured the solution in three main tiers, all controlled by UniStream and connected over Modbus TCP.

- Tier 1. Chemical Mixing Unit (CMU)

The CMU is the core preparation area. A UniStream controller manages intake, dosing, recipe execution, and transfers.

Instrumentation and Control:

• 65 hydrostatic level sensors + 65 high-level switches monitor 8 raw-material tanks, 28 storage chemical tanks and 28 end user tanks.
• 39 electromagnetic flowmeters + 2 Coriolis mass flowmeters ensure accurate dosing into the mixers, transfer to storage tanks and billing to end user tanks.
• 114 valves (47 three-way, 67 two-way) equipped with inductive position feedback for verification.
• Automated recirculation sequences maintain chemical integrity in storage tanks.
• Transfer logic moves finished chemicals to storage and triggers mandatory flushing of the single-line pipeline after each operation.

- Tier 2. Chemical Distribution Center (CDC)

Three UniStream 10” controllers coordinate storage and FIFO distribution to end users:

• FIFO request queue: the PLC receives level-based refill requests from user tanks and processes them in first-in, first-out order.
• Live shipment metrics shown on the HMI:
  • AV: volume of current shipment (liters, green).
  • DD: total volume shipped during the current day (liters, yellow).
  • MM: total volume shipped in the current month (liters, light blue).
• Destination indication: enables operators to see which user tank is currently being filled.
• Distributed resilience: if Modbus communication is lost, each CDC controller automatically switches to manual/local mode and continues supplying chemicals.

- Tier 3. End-User Stations (AutoChem)

Each consumer tank is managed by a local UniStream controller that handles local tank monitoring and request logic:

• Overview screens showing tank levels and feed valve states for each chemical.
  
• Per-tank detail screens where engineers configure refill start and stop levels.
• A guided three-step sequence:

1. End user requests a chemical
2. CDC verifies line availability and commands the destination valve
3. Once valve position is confirmed, shipment begins automatically

This handshake-style control ensures the pipeline opens only when both sides are ready, reducing risk of spills.

Software Design with UniLogic

• Transfer and flushing progress.
• Maintenance and calibration screens to disable tanks, test valves, and calibrate level sensors without affecting other parts of the system.

Results: High Availability, High Precision, and Scalability

Benefits