ISDN Data and Telephony Protocol Engine (inc. X.25)
CMX228
%A2 (CSD Protocol)
Selects the protocol to be used for the circuit switched data calls. Note that %A2 cannot be changed
while a B or D-channel call is active.
Value
Description
2 (default)
V.120 Rate Adaption on B-channel.
Voice Calls.
X.25 Rate Adaption on B-channel.
3
4
5
6
X.25 packet calls on D-channel.
X.25 to a packet switched data network reached by a B-channel data
call. This involves a two stage call set up. Firstly a circuit switched call
must be established to the X.25 node, followed by a virtual call to an X.25
destination. The ATD command is used for both call requests.
PPP.
15
20
Transparent protocol.
1.5.6.2.1 X.25 Virtual Circuit Parameters
All %B registers can be read using the %Bn? command.
%B0 (X.25 Receive Window Size)
Defines the maximum number of X.25 packets that may be received before an acknowledgement is
sent.
Value
Description
0 (default)
Use the default value appropriate to the type of call, without negotiation,
see %D registers.
1 to 7
Negotiate the receive window size according to the value entered.
%B1 (X.25 Transmit Window Size)
Defines the maximum number of X.25 packets that may be transmitted before an acknowledgement is
expected. Use of the default value is recommended.
Value
Description
0 (default)
Use the default value appropriate to the type of call, without negotiation,
see %D registers.
1 to 7
Negotiate the transmit window size according to the value entered.
%B2 (X.25 Receive Packet Size)
Defines the maximum number of bytes that may be received in an X.25 packet.
Value
Description
0 (default)
Use the default value appropriate to the type of call, without negotiation,
see %D registers.
7
8
9
10
Negotiate for a maximum 128 bytes per packet.
Negotiate for a maximum 256 bytes per packet.
Negotiate for a maximum 512 bytes per packet.
Negotiate for a maximum 1024 bytes per packet.
%B3 (X.25 Transmit Packet Size)
Defines the maximum number of bytes that may be transmitted in an X.25 packet.
ã 1999 Consumer Microcircuits Limited
ã 1999 Chiron Technology Limited
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D/228/1
CMLMICRO [ CML MICROCIRCUITS ]
