Hi, I start to work in a prototype with a module BG95-M3, and only for test it, whit a serial connection I send it simple commands, like ATI, but in the serial port always receive the same data -1, someone knows something about that? or how I can solve it? Hahahah someone can help me please?
I show you my monitor serial outputs 
14:14:58.400 → Start
14:14:59.205 → ***********************
14:14:59.205 → ATI
14:14:59.445 → -1
14:15:00.454 → AT+GMI=?
14:15:00.695 → -1
14:15:01.706 → Start
14:15:02.508 → ***********************
14:15:02.508 → ATI
14:15:02.748 → -1
14:15:03.758 → AT+GMI=?
14:15:03.998 → -1
14:15:05.009 → Start
14:15:05.810 → ***********************
14:15:05.810 → ATI
14:15:06.051 → -1
14:15:07.066 → AT+GMI=?
14:15:07.307 → -1
14:15:08.308 → Start
14:15:09.112 → ***********************
14:15:09.112 → ATI
14:15:09.353 → -1
14:15:10.356 → AT+GMI=?
14:15:10.594 → -1
14:15:11.596 → Start
14:15:12.404 → ***********************
14:15:12.404 → ATI
14:15:12.640 → -1
14:15:13.640 → AT+GMI=?
14:15:13.880 → -1
