The key specifications of the Relay Module, For 4", HMI Display are — Relay: Type 8x Relays (SPDT or DPDT); Module: Mounting DIN Rail; PLC Communication: RS-232, RS-485, Modbus (varies by PLC); Operating Temperature: 0°C to 55°C. These specifications are based on the standard GEM Equipments design; always verify against your machine's requirement before use. GEM Equipments Pvt. Ltd., established in 1984 and ISO 9001:2015 certified, is one of India's leading manufacturers of compressed air dryers, cooling towers, industrial chillers, and compressed air treatment accessories, based in Coimbatore, Tamil Nadu.