The Siemens SIMATIC S7-1500 Analog Input Module AI8 RTD 6ES7 531-7KF00-0AB0 is a module designed for the SIMATIC S7-1500 series of programmable logic controllers (PLCs). That can be configured for various types of signals, including resistance temperature detectors (RTDs).
You can likely find this module through Siemens’ authorized distributors and partners in your region. You may want to contact companies specializing in industrial automation and control systems in Dhaka or other industrial areas.