<https://www.tudong-ttc.com/san-pham/6es7321-1bp00-0aa0-s7-300-digital-input-sm-321/#product>
<http://schema.org/description>
" Model :6ES7321-1BP00-0AA0\r\n\r\n Description : SIMATIC S7-300 digital input SM 321, Isolated in groups of 16, 64 DI, 24 V DC, 3ms, Sink/source input Terminal blocks 6ES7392-1.N00-0AA0 and cable 6ES7392-4...0-0AA0 required"
<https://www.tudong-ttc.com/san-pham/6es7321-1bp00-0aa0-s7-300-digital-input-sm-321/>