Why is the modem polling but not responding when trying to dial in Windows 7?

Question

Windows

Good afternoon. There is a modem consisting of a Quectel M72 + USB/UART module on a CP2102. He stood at work at one workplace, and when you try to transfer him to another workplace, he stubbornly refuses to work. The drivers are the same, Windows 7. When you return to the old place, it works without problems, so I sin on Windows. All USB ports and several computers have been tested. It is created as a standard 9600 modem according to the instructions. Interrogated successfully in 2 out of 3 cases on the diagnostics tab. The created connection, when trying to connect using standard means, stubbornly beats the 692nd error. Although, if you immediately interrogate the modem on the diagnostics tab in the task manager, then it is interrogated. I monitored the port through HDD Monitoring Studio - with a standard connection, it does not even respond to the first command - AT. When polled, the first command is not AT, a ATE0Q0V1AT+FCLASS=? and then a bunch of OKs and other answers and commands. After the 692nd error in the modem log is the following:

12-06-2017 12:26:32.190 - File: C:\Windows\system32\tapisrv.dll, Version 6.1.7601
12-06-2017 12:26:32.190 - File: C:\Windows\system32\unimdm. tsp, Version 6.1.7601
12-06-2017 12:26:32.190 - File: C:\Windows\system32\unimdmat.dll, Version 6.1.7601
12-06-2017 12:26:32.190 - File: C:\ Windows\system32\uniplat.dll, Version 6.1.7600
12-06-2017 12:26:32.190 - File: C:\Windows\system32\drivers\modem.sys, Version 6.1.7600
12-06-2017 12:26 :32.190 - File: C:\Windows\system32\modemui.dll, Version 6.1.7600
12-06-2017 12:26:32.190 - File: C:\Windows\system32\mdminst.dll, Version 6.1.7600
12- 06-2017 12:26:32.190 - Modem type: Standard modem 9600 bps
06-12-2017 12:26:32.190 - Modem INF file: mdmgen.inf
12-06-2017 12:26:32.190 - Section of the modem INF file: Gen96
12-06-2017 12:26:32.190 - Correspondence to the hardware code (ID): mdmgen96
12-06-2017 12:26:32.252 - 9600, 8,N,1, ctsfl=1, rtsctl=2
12-06-2017 12:26:32.268 - Modem initialization.
12-06-2017 12:26:32.268 - DSR signal strength is weak during modem initialization. Check that the modem is turned on.
12-06-2017 12:26:32.268 - Low CTS signal during modem initialization.
12-06-2017 12:26:32.284 - Sent by: AT
12-06-2017 12:26:34.285 -
Waiting for modem response one more try
12-06-2017 12:26:34.285 - 9600.8,N,1, ctsfl=1, rtsctl=2
2017-06-12 12:26:34.300 - DSR signal strength is weak during modem initialization. Check that the modem is turned on.
12-06-2017 12:26:34.300 - Low CTS signal during modem initialization.
12-06-2017 12:26:34.316 - Sent by: AT
12-06-2017 12:26:36.317 -
Waiting for modem response another try
12-06-2017 12:26:36.317 - 9600.8,N,1, ctsfl=1, rtsctl=2
12-06-2017 12:26:36.333 - DSR signal level is weak during modem initialization. Check that the modem is turned on.
12-06-2017 12:26:36.333 - Low CTS signal during modem initialization.
12-06-2017 12:26:36.348 - Sent by: AT

At the same time, I open the modem port in the terminal (Terminal 1.9b), send AT $ 0D $ 0A and get OK on all attempts, except for the first one after connecting.
What the hell is going on, I'm confused....

Answer 1

Problem solved. Device Manager - Modems - Properties of our modem - Advanced communication settings - Change defaults - Flow control Replace "Hardware" with "None". After that, everything is like clockwork.