Custom Farm Automation PCBA

Custom Farm Automation PCBA | 32-Channel Anti-Interference Input & 28-Channel Relay Output

This custom PCBA is tailored exclusively for poultry and livestock farm environmental control cabinets, refined from real on-site problems we've encountered in agricultural automation projects. Measuring 220mm × 285mm, it perfectly matches mounting hole dimensions of standard farm control cabinets. Most farm equipment suppliers retain existing cabinet molds to cut tooling costs, so this board's layout prioritizes mechanical compatibility with finished enclosures, rather than following generic universal PCB designs.

Equipped with 32 opto-isolated digital input channels, it solves a common farm pain point: unstable long-distance sensor signal transmission. On actual breeding sites, temperature, humidity, water level and door limit sensors are often installed up to 45 meters away from control cabinets. Signal cables inevitably run parallel to high-power fan and heater wiring, causing severe electrical interference. Each input integrates a dedicated 2.2kΩ pull-up resistor and RC filter circuit, effectively eliminating signal surges and false triggering that plague ordinary control boards. It supports 12V–24V dry contact and level signals, compatible with nearly all mainstream agricultural sensors on the market.

The board features 28 relay output channels for various farm field loads. Each relay handles 10A 250VAC resistive loads, with a practical 5A limit for inductive motor loads such as ventilation fans and curtain rollers - a verified threshold summed up from years of on-site deployment. Unlike low-cost basic boards lacking protection, every relay coil is fitted with a freewheeling diode to absorb reverse voltage surges from frequent motor start-stop cycles. This small but vital upgrade prevents main control chip burnout, one of the most frequent failures in budget farm PCBA solutions. High-current output traces adopt 2.0mm thick copper, keeping temperature rise below 28K during continuous 8A full-load operation for reliable round-the-clock farm operation.

Built with industrial-grade components, the board operates stably across -10℃ to 60℃, adapting to farms' harsh conditions: high humidity, dust buildup and corrosive ammonia gas. Optional conformal coating delivers extra moisture and corrosion resistance to extend service life. It uses 5.08mm pluggable terminal blocks with 64 ports, clearly zoned for power, signal input and load output. This partitioned layout simplifies wiring and troubleshooting for field electricians working in dim, cramped cabinet spaces.

The onboard MCU supports independent logic linkage, enabling automatic temperature-based fan operation, over-temperature heater cutoff and water level-linked pump control. Two reserved UART headers support Modbus-RTU expansion, allowing data upload to upper monitoring systems for centralized farm management. During prototype testing, I noticed the original terminal layout sat too close to cabinet metal edges, blocking thick on-site power wires. We fixed this by shifting the terminal group 7mm inward with no circuit modifications, purely optimizing for real-field assembly. All mass-produced units undergo 100% ICT testing and full-channel aging simulation to ensure every channel functions flawlessly before delivery.