Rockwell Automation 57C570 AutoMax PC3000 User Manual - Manual (Page 166)

14Ć8
For example, if the target module for request 1 was
located in I/O group 3, bits 9Ć11 of register 833 should
contain the value of 3.
833: xxxx 0110 xxx0 0111
14.3.2 Specifying a Read or Write Operation
You must define a blockĆtransfer request to be either a read or a
write request. To do this, set bit 15 of the variable associated with
the second word within the request's status and control table, which
is labeled Rack/Slot/Group/Req.
To specify this type of reĆ
quest:
Set bit 15 of the variable associated with the
request's Rack/Slot/Group/Req register to:
read 1
write 0
For example, to specify blockĆtransfer 1 to be a read request, bit 15
of register 833 would contain a value of 1.
833: 1xxx 0110 xxx0 0111
14.3.3 Specifying the Length of a BlockĆTransfer
The length of the blockĆtransfer specifies how many words of data
will be read from or written to the target blockĆtransfer module per
blockĆtransfer request. Specify the length of the blockĆtransfer
request by loading a value of 1Ć64 into the variable associated with
the Length of Block Xfer register within the blockĆtransfer status and
control table. This parameter corresponds to the third word within
this table.
For example, if you wanted to transfer 10 words of data during
blockĆtransfer request 1, you would load a value of 10 into
register 834.
14.3.4 Specifying the Update Time of the BlockĆTransfer
Setting an update time determines if a blockĆtransfer is continuous
or nonĆcontinuous. You specify an update time for a blockĆtransfer
request within the variable associated with the register labeled
Update Time (the fourth word of the request's blockĆtransfer status
and request table). The time you enter is in intervals of 10 ms.
To specify this type of blockĆtransfer: Enter this within the request's
Update Time register:
continuous a value in units of 10 ms
Update time (ms) = n 10,
where n is the number you load
into the register.
nonĆcontinuous a value of 0
For example, if you wanted blockĆtransfer request 1 to execute every
30 ms, you would place a value of 3 into register 835.
For more information about continuous and nonĆcontinuous
blockĆtransfers, see section 14.1.2.