Siemens 6ES7551-1AB00-0AB0 SIMATIC S7-1500, TM POSINPUT 2 Counter and position detection module (Siemens 6ES75511AB000AB0)
Siemens 6ES7553-1AA00-0AB0 SIMATIC S7-1500, TM PTO 4 Interface board for stepper drives (Siemens 6ES75531AA000AB0)