Siemens branded I/O Modules used with the 353R product are no longer available. Generic modules may be sourced through GE referencing their 8000- series part numbers
SIPLUS S7-300 PS305 -25...+60 DGR C WITH CONFORMAL COATING ACCORD. EN50155 T1 KAT 1 KL A/B BASED ON 6ES7305-1BA80-0AA0 . STABILIZED POWER SUPPLY INPUT: 24-110 V DC OUTPUT: 24 V/2 A DC