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Chapter 4 - V.22bis Commands
Multi-Tech Systems, Inc. MT2456SMI-22 SocketModem Developer’s Guide 35
V.22bis S-Parameters
The S-Parameters are summarized in the S-Parameter Table along with their default values which may be loaded at
any time by using the Z command. Registers or register fields quoted as “reserved” are reserved for current or future
use by the firmware or are permanently overridden by PTT limitations. For the latter, control of the equivalent
functionality is available with Blacklisting options.
All bit-mapped registers are read-only. The appropriate AT command, which controls the relevant bits in the S-
Parameter should be used to change the value.
S - Read/Write S-Parameter
The modem selects an S-Parameter, performs an S-Parameter read or write function, or reports the value of an S-
Parameter.
n Establishes S-Parameter n as the last register accessed.
n=v Sets S-Parameter n to the value v.
n? Reports the value of S-Parameter n.
The parameter n can be omitted, in which case the last S-Parameter accessed will be assumed. The S can be
omitted for AT= and AT?, in which case the last S-Parameter accessed will be assumed. For example:
ATS7 establishes S7 as the last accessed register.
AT=40 sets the contents of the last register accessed to 40.
ATS=20 sets the contents of the last register accessed to 20.
If the number "n" is outside the range of the S-Parameters available, the modem will return the ERROR message. If
the value “v” is outside the range permitted for a given SParameter, the modem will return the ERROR message.
Input and output are always in decimal format. Note that some S-Parameters are read-only.
In some cases, writing to the S-Parameter will appear to be accepted but the value will not actually be written.
Due to country restrictions, some commands will be accepted, but the value may be limited and replaced by a
maximum or minimum value.
Minimum, maximum, and default values for S-Parameters may be altered by inserting a country profile using patch
code.