HORNER HE800JCM200, Руководство пользователя

Страница: 12 / 20

PAGE 12 14 MAY 2002 CH. 2
MAN0484-01
2.4.4 Low Priority Request
When the transmit channel is used to a low priority request to a device on the network then the first 4
%AQs, 2 %Qs, 2 %Is, and a defined number of %Rs are used.
Low Priority Request Register Use:
The %AQs contain the information to be transmitted. The %AQs need to be loaded with the appropriate
data before %Qx is toggled from a 0 to 1 to initiate the transmit. The %Rs will contain the request data if
%Ix+1 is not set (No transmit error).
The following is a detailed description of the %AQ and %AI data:
%AQx contains the PGN that is being requested.
%AQx+1 contains the destination address of the device that contains the requested data.
%AQx+2 contains 2 bytes for the requested PGN and the number of bytes of requested data to store in
the %R registers [CURRENTLY FIXED AT A MAX OF 10 BYTES (2 for PGN + 8 for data].
%AQx+3 contains the starting %R register where the requested data will be stored.
The remaining %AQs are not used.
%Rx contains the requesed PGN that is associated with the following data
%Rx+1 contains data byte 1
%Rx+2 contains data byte 2
%Rx+3 contains data byte 3
%Rx+4 contains data byte 4
%Rx+5 contains data byte 5
%Rx+6 contains data byte 6
%Rx+7 contains data byte 7
%Rx+8 contains data byte 8