User`s guide

4: ADCCP NRM Operations
DC 900-1317J 91
4.1.5 Information Transfer State Operation
Once a station is in the information transfer state, data transfer is allowed. Selection of
ADCCP option 8 or 9 for NRM operation changes data flow between primary and sec-
ondary stations so that it is in one direction only.
In this state, the client transmits data by sending DLI_PROT_SEND_NORM_DATA packets to
the ICP; the client receives data in the form of
DLI_PROT_RECV_DATA packets. When the
remote station acknowledges receipt of the data, the client receives a
DLI_PROT_RESP_NORMAL_ACK packet. The iProtModifier field in the this packet identifies the
number of
DLI_PROT_SEND_NORM_DATA packets acknowledged and always refers to the
oldest packets transmitted for the specified station.
The ICP acknowledges DLI_PROT_SEND_NORM_DATA packets in the order in which they
were sent. However, if a station reset occurs, subsequent
DLI_PROT_RESP_NORMAL_ACK
packets acknowledge DLI_PROT_SEND_NORM_DATA packets sent following reset confirma-
tion.
If ADCCP option 1 is enabled, the client may initiate an exchange of station identifica-
tion with a remote station by sending a
DLI_PROT_SEND_EXCHANGE_ID packet to the ICP;
the ICP replies with a
DLI_PROT_RECV_EXCHANGE_ID packet after the remote station
responds to the associated XID request on the link. The client must not mix data trans-
fer with exchange ID requests; normally, the exchange of ID is done once, prior to the
transfer of any data.
If ADCCP option 1 is enabled, the client may also receive unsolicited
DLI_PROT_RECV_EXCHANGE_ID packets for local stations. The client must respond by send-
ing a
DLI_PROT_SEND_EXCHANGE_ID packet to the ICP.
If ADCCP option 4 is selected, the client may send and receive Unnumbered Data pack-
ets. However, no mechanisms for data flow control or acknowledgment of data recep-
tion are defined for Unnumbered Data packets. It is the user’s responsibility to limit
unnumbered data flow so that the ICP buffering capacity is not exhausted.