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Is it my imagination or is RS-232 a de facto data comm standard for PLC's? If so, why?
I recently purchased two small fixed I/O PLC's of different manufacturers and each had a 9-pin D-type connector for 232 data comm. Neither plc offered a more contemporary data comm alternative such as 485, 488 or even better, USB. Since the programming will be performed on a USB-based machine and since the 232 to USB adaptor can frequently add an additional layer of aggravation, why does rs-232 continue to appear on new PLC's? Thanks.
I recently purchased two small fixed I/O PLC's of different manufacturers and each had a 9-pin D-type connector for 232 data comm. Neither plc offered a more contemporary data comm alternative such as 485, 488 or even better, USB. Since the programming will be performed on a USB-based machine and since the 232 to USB adaptor can frequently add an additional layer of aggravation, why does rs-232 continue to appear on new PLC's? Thanks.