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Appendix B – Modem Commands
POS V22 Direct Commands
The following parameters within this section are available when the Call Type index is set to POS V22 Direct
(:m112=64). The values of the following timing control parameters (indexes) are configured in milliseconds, but
the DSP processing cycle occurs once every 6 ms. As a result, the timing that can be expected is as if the
value is rounded up to the next higher 6 ms interval. A setting of 0 will result in a 6 ms interval.
Intercharacter Delay
Index 253 Default = 0
The minimum setting is 0. The maximum setting is 255.
This index defines the intercharacter delay - meaning how long the modem waits for the next incoming
character (coming from the line\remote POS) before it sends data in the upstream direction (to the host). If this
index is set to zero (it's default), the intercharacter delay time is not active; pending upstream data will be
delivered whenever there is no other data queued for processing in the upstream direction.
The units are in increments of 10 milliseconds. A value of 1 is the minimum. So at:m253=1 means the modem
will wait up to 10 milliseconds for the next incoming character before it gives the data it has to the internal
driver. If the remote POS connects at 2400 bps and sends 350 bytes, that means the modem in the
MultiAccess will receive 1 byte every 4 milliseconds - so using :m253=1 means you should receive all 350
bytes at once.
Pause Before Answer Tone Index 173 Default 300
The minimum setting is 0. The maximum setting is 600.
This index defines in milliseconds how long the modem waits before it generates quick connect answer tones
after it receieves the answer command.
Answer Tone Duration Index 174 Default = 660
The minimum setting is 0. The maximum setting is 1200.
This index defines the duration of the answer tone from the MultiAccess modem. The unit value is 1
millisecond. The default value is 660 milliseconds, The actual recommended minimum value is currently not
known. We successfully tested with 100 milliseconds. Answer tone is traditionaly used to turn off the PSTN
echo cancellors.
PAUSE AFTER ANSWER TONE
Index 175 Default = 66
The minimum setting is 0. The maximum setting is 300.
This index controls the duration of the pause after the answer tone.
BELL212A V22 TX BINARY ONES DURATION Index 176 Default = 2400
The minimum setting is 0. The maximum setting is 4800.
This index controls the duration that the answering port transmits unscrambled binary ones while waiting to
detect scrambled binary ones in Bell 212A and V.22 or the S1 sequence at V.22bis. Failure to detect
scrambled binary ones within this time period will cause the port to fall back to V.21/Bell 103.
V22BIS TX DIBIT DURATION
Index 178 Default = 84
The minimum setting is 0. The maximum setting is 360.
This index controls the length of time that the answering port transmits the V.22bis unscrambled repetitive
double dibit pattern (S1) following detection of the S1 sequence from the client modem.
MultiAccess Communications Server MA30120 User Guide
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