Texas Instruments 990 User Manual page 240

Communications Structures
where:
Byte 0 is the general format identifier, 0001, followed by
the virtual channel group (VCG) number.
Byte 1 is the logical channel number (LCN). VCG and LCN
together form the logical channel identifier (LeI).
Byte 2 is the reset confirmation identifier.
D.3.3 Receive Not Ready Packet
The conditions to be considered for the RNR packet are as
follows:
*
When an RNR is transmi tted, that is, when the sender is
unable to receive data packets on the PVC. This
condition clears when any of the following occurs:
The transmission of a receive ready packet after
the RNR condition is corrected.
The reception of a reset request packet.
The transmission of a reset request packet.
*
When an RNR is received, that is, when the receiving
station is unable to send data packets on the PVC. This
condition clears when any of the following occurs:
A receive ready packet is received
A reset request packet is received
A reset request packet is sent and a reset request
or a reset confirmation packet is received in
reply.
After receiving an RNR, the receiving station can continue to
receive data packets on the PVC.
When the RNR condition has persisted for too long (as
by the receiver of the RNR) a reset request
transmitted.
determined
packet is
The peR) and peS) counters are not reset when an RNR is sent or
received. If the station that sent the RNR continues to send
da ta packets, the P (S) counter is upda ted wi th each da ta packet
sent. The peR) counter indicates the next expected peS) count if
the RNR condition is cleared without resetting.
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