CMX228S1 MX-COM, Inc., CMX228S1 Datasheet - Page 10

• Manufacturer Part Number: CMX228S1
• Description: ISDN data and telephony protocol engine with x.25
• Manufacturer: MX-COM, Inc.

ISDN Data and Telephony Protocol Engine with x.25
4.2
On power-up, the CMX228 assumes its default values, which are factory programmed into the firmware. It
then performs a self-test, during which all of the LED pins and the ILFI pin are held high for 3s. If the test is
unsuccessful, the CMX228 remains in this condition.
If the test is successful, the CMX228 reads its preset values from the attached EEPROM and examines the
state of the ISDN link (i.e. Layer 1) before commencing normal operation. On power-up, the ISDN link is de-
activated, the POTS port is assumed to be on-hook, ringing is disabled and the RS232 port is in the Hayes
command state.
4.3
Simultaneous voice and data calls are possible but only one of each type. If a call is active (e.g. ringing,
connected or clearing down) and an incoming call of the same type (data or voice) is received, that call will be
rejected with user busy as the cause. Incoming calls are firstly checked for other calls present, then the MSN
is checked for validity, then the channel mapping, so that responses will be handled accordingly.
When channel mapping is enabled, outgoing calls will request the channel enabled. When not enabled, a
request for any channel is made. If no free channels are available for outgoing calls, a locally generated busy
tone is returned to the analog port or the appropriate Data Call Result Code is returned to the digital port.
4.3.1
Activation occurs in the following circumstances:
The Terminal Endpoint Identifier (TEI) is either negotiated (Hayes register !C7 = 64) or fixed
(Hayes register !C7 = 0 to 63). Line powering of the CMX228 is not supported.
The 'AR' indicator (LED8) toggles between high and low states when the CMX228 is powered up, and
remains constantly low once the CMX228 identifies an activated ISDN line.
ISDN line power detection is not implemented and the CMX228 will negotiate a new TEI on any new network
activation.
4.3.2
De-activation or line disconnection causes the TEI to be removed. Upon re-connection the CMX228 will only
be re-activated and request a new TEI when one of the conditions in the above section is met.
4.3.3
If the line failure detection parameter is enabled (either via the POTS port or via the RS232 interface) the
CMX228 will check that Layer 2 communications are active every sample period of 30 seconds. If Layer 2
communications are not active, the CMX228 will attempt to activate them. If they remain inactive for 2 sample
periods, the line is deemed to have failed, so then the ILFI pin is set high and both RING1 and
are set low. The CMX228 continues to attempt to activate the line and if it becomes active and stays active
for 2 sample periods, then the ILFI pin is set low and RING1 and
settings.
4.3.4
Incoming voice calls and calls from analog lines are directed to the analog port and all other incoming calls
are directed to the RS232 port.
MX-COM, Inc
4800 Bethania Station Road, Winston-Salem, NC, 27105-1201, USA
www.mxcom.com tel: [phone] 744 5050 fax: [phone]
All trademarks and service marks are held by their respective companies
Initialization
ISDN Interface
Activation
The ISDN network activates.
The device connected to the analog port goes off hook.
The device connected to the data port sends a Hayes dial command.
De-activation or Line Disconnection
Line Failure Detection
Incoming Calls
10
RING pins are restored to their default
1
2000 Chiron Technology Limited
CMX228 Advance Information
Doc. # 20480216.001
2000 MX-COM, Inc.
RING pins
1