User`s guide

3: ADCCP NRM DLI Functions
DC 900-1317J 61
the ICP uses selective broadcast addressing. If bit 1 is reset to zero and bit 2 is set to one,
the ICP uses general broadcast addressing. If both bits 1 and 2 are set to one, the ICP
returns a
DLI_PROT_RESP_ERROR packet to the client.
When selective or global addressing is used, the client must specify the link ID and zero
the station ID, since the data is intended for multiple stations on the link. Prior to using
the selective broadcast addressing mode, the client must set the multipoint list (see
Section 3.4.13).
The ADCCP protocol defines a flow control procedure for I-frames. In the client/ICP
interface, flow control is implemented for
DLI_PROT_SEND_NORM_DATA packets. The client
may send several
DLI_PROT_SEND_NORM_DATA packets to the ICP while awaiting acknowl-
edgment in the form of
DLI_PROT_RESP_NORMAL_ACK packets.
The client must limit the total number of unacknowledged DLI_PROT_SEND_NORM_DATA
packets to avoid causing buffer congestion on the ICP. If the client overloads the ICP,
the ICP simply stops accepting input from the client; the client cannot send additional
control packets to the ICP until the ICP’s buffer congestion clears. If buffer congestion
occurs on the ICP, an application in the client attempting to write a control packet to
the ICP experiences delayed I/O completion, but no packet is actually lost.
3.4.9 DLI_PROT_RECV_DATA Packet
This packet is valid for primary stations unless the client has enabled ADCCP option 8
(see Section 3.4.20.2) for the specified primary station. The packet is valid for secondary
stations unless the client has enabled ADCCP option 9 for the specified secondary sta-
tion. The ICP specifies the
usProtCommand field (DLI_PROT_RECV_DATA), the iProtModifier
field, the link ID, the usProtXParms[0] field (station ID), the usProtXParms[1] field (data
size), and the data field contents.
For NRM secondary stations, bits 1 and 2 in the iProtModifier field indicate the address-
ing mode in the received frame. If both bits 1 and 2 are reset to zero, normal individual
station addressing is indicated. If bit 1 is set to one and bit 2 is reset to zero, selective