I take 2 new gr64 modems and start experiments using Windows Hyperterminal on both. Calling modem as master, answering modem as slave. I’ve changed default settings on both modems:
at+ipr=9600, ats0=1, at+ifc=0,0,1, at&d0.
*EIDSUM: GR64001/55 400 07W19 R3B GR64 “GR64/30”
After connection set up (both answered CONNECT 9600) i send nothing in line. After 2-3 minutes master or slave modem prints NO CARRIER and disconnects (answer zero on at+cpas). Other modem stays in connection for a period of at least 20 minutes until I send him manually +++AT and then ATH. After accepting ATH modem thinks about 1-2 minutes and prints OK (after this answers zero on at+cpas).
But if I disconnect modems manually using +++AT and then ATH, both modems prints NO CARRIER immediately and all OK - I can set up a new connection immediately.
It seems if one modem lost a connection, 2nd modem stays in line for a undetermined time. It is a modem bug or what?
Send a command ATD to master and wait. Sometimes slave modem don’t prints RING. Аnd master prints nothing. Send a +++AT to master modem, get an OK answer. Send at+cpas, get 3 (ringing state). Send ATH and modem hangs up (for a 1 hour period at this time). I typing AT-commands in hyperterminal and see neither reaction no my characters. It is a modem bug or what?
Or may be this device only for GPRS and its GSM stable working not guaranteed?
Or may be exists a new firmware update? I can’t find it on this site. Anyone send me a link to it, please.