User`s manual

U.S. Robotics I-modem Command Reference
Appendix A: Alphabetic Command Summary • Page A-8
O0 Return online (normal).
O1 Return online and retrain. Use O1 if there were errors in a non-ARQ data
transfer.
Qn Enable or disable the display of result codes.
Q0 Display result codes.
Q1 Suppress result codes (quiet).
Q2 Suppress result codes when answering.
S$ Display help screens for the S-registers.
Sr=n Set S-re
gister value: r is any S-register; n must be a decimal number between 0 and
255.
Sr.b=n Set a bit-mapped register: r is the S-register, b is the bit, and n is 0 (off) or 1 (on).
Sr? Query contents of S-register r.