Integrator’s Reference Manual
5-10 80-99208-1 Rev. D
Table 5-3. Port Arbitration Behavior
Control
Port Active Data Port
Active Port Behavior
No No Control an d Data ports are inactive and modem is pow ered
down unless the Diagnostic port is active.
No Ye s The Data p ort processes all data a nd AT commands,
including the following:
■Online-Command mode is supported on the Data port.
■All port configurati on commands apply to the D ata port
as defined in Port(s) Affected by AT Commands on page
5-13.
■If a non-data call (e.g., Markov, Loopback) is already
active when a call is attempted with the ATD command,
the BUSY result is returned. If a data call is active, a NO
DIALTONE result is returned.
■DTR cannot be used to terminate a call or enter
Online-Command state (AT&D2 or AT&D1
configurations), unless the Diagnostic port is active.
Note: This is because the modem powers down if all
DTRs are low. DTR can be used to terminate the call or
enter Online-Command mode, although the modem will
power down after approximately 1 second.
Yes No All AT commands are processed on the Control port. Data
calls are not supported because the Data port is inactive.
■All data calls initiated using the ATD command return
NO DIALTONE.
■ATD<phone number> returns NO DIALTONE.
■The ATD command with #627568(Markov test call) or
#56672225 (Loopback test call) dial strings initiates a
call if a call is not already active. If a call is already
active when the call is attempted, a BUSY result is
returned.
■Port configuration commands apply to the Data port
and Control port as defined in Port(s) Affected b y AT
Commands on page 5-13.
■The online escape sequence “+++” surrounded by guard
time is ignored.
■Online-Command mode command ATH returns OK.
ATH will terminate an active test call.
■Online-Command ATO returns NO CARRIER.