Rockwell Automation GMLC Reference Manual - Manual (Page 719)

Publication GMLC-5.2 - November 1999
682 Using the RIO Adapter Option
When configured as an adapter, both dedicated (pre-defined) and user-
defined discrete I/O are available. It provides 12 dedicated discrete inputs
for direct control of certain manual functions and 12 dedicated discrete
outputs for basic status reporting to the PLC. Up to 100 user-defined
inputs and 100 user-defined outputs are also available. These I/O are
transferred once each RIO scan.
Block Transfers
Block transfers are used to transfer parameter values, recipes, status, and
other non time-critical data such as axis position, velocity, etc. for display
purposes. Up to 64 words (128 bytes) of data can be transferred from the
motion controller to the PLC or from the PLC to the motion controller in
each block transfer. In addition, data can be transferred in one of four
different numeric formats as required by the RIO scanner or other devices
on the RIO link. Note that compared to direct transfers, there can be a
relatively long time between block transfers depending on the scan rate of
the PLC and the number of devices on the RIO link.
Block transfers allow the PLC to read and write variable, data parameter,
data bit, and cam table values directly in binary format to the motion
controller. The PLC stores these values in data files.
Only the RIO scanner (in the PLC or host computer) can initiate block
transfers. However, the motion controller can request a block transfer
from the PLC using a user-defined discrete output.
Important: Do not create a PLC program in which a Block Transfer Read
and a Block Transfer Write are read in the same I/O scan. A
RIO error occurs.
See Using Block Transfers in this chapter for more information on
working with block transfers.