The MDC-711 supports up to 250 total polling definitions, with each definition allowing up to 125 registers when using firmware version 1.08 or later. Modbus protocol limits still apply, with a maximum of 255 registers for Function Codes 01 and 02 and 126 registers for Function Codes 03 and 04 per Modbus command. The internal shared memory is limited to 9,600 registers per data type (AI, AO, DI, and DO). Polling is executed sequentially by COM port and polling order, which can impact scan times in large systems. Monitoring polling performance through the web interface is recommended when optimizing high-density Modbus networks.
