ESI-1 4-20 mA to S-Link interface

The Sleipner ESI-1 interface is designed for integrating third-party control systems with Sleipner S-Link thrusters. It converts 4-20mA analog signals into proportional commands for bow and stern thrusters, providing extended compatibility with various marine equipment.

Connectivity and Control

The ESI-1 features two 4-20mA analog inputs (AI1 and AI2) dedicated to proportional thruster control. A digital input (DI1) allows activation of these analog inputs via a 12V or 24V control signal. The unit also includes two normally open relay contacts (RO1 and RO2): RO1 provides feedback on ESI-1 activation, while RO2 offers specific feedback for hydraulic thrusters. For proportional control, a 12mA signal holds the thruster at idle, 4mA corresponds to 100% port thrust, and 20mA to 100% starboard thrust. Communication is via the S-Link bus, a CAN-based control system.

Technical Specifications and Compatibility

The interface requires an external 8–31V DC power supply, with a recommended 5 A fuse. The relay outputs can handle a maximum current of 10 A. The 4-20mA analog inputs are non-isolated resistive loads, requiring the connected source to provide loop power. The DI1 digital input is opto-isolated from the power ground. Dimensions are 156.5mm height, 61.3mm depth, and 212mm width, with a net weight of 0.5kg. The ESI-1 is compatible with all Sleipner thrusters in the SEP, SHP, SAC, and E series, including retractable thrusters and the Automatic Main Switch (AMS).

S-Link Features and Safety

As part of the S-Link system, the interface benefits from compact, color-coded, and keyed waterproof connectors for simplified installation, along with a scalable design featuring various cable lengths and extensions. The operational priority of the ESI-1 is configurable: by default, other S-Link devices sending thrust commands have higher priority, but it can be adjusted to operate with the same priority as other devices. An integrated safety mechanism ensures the thruster controller outputs the highest received thrust signal and stops in case of conflicting directional signals.