Rockwell Automation GMLC Reference Manual - Manual (Page 814)

Publication GMLC-5.2 - November 1999
Understanding Discrete Data Transfers 777
The rate at which the GML Commander program updates its outputs
depends on the I/O file update rate (see Defining the I/O Configuration)
and the servo update rate (see Enabling M File Transfers). In order for the
SLC to access this new data, it must update its inputs. The SLC accesses
this new data during the next input scan. The rate at which the SLC
program updates its inputs depends on the size of the user's program.
See the SLC 500 Reference Manual (publication 1747-6.15) for specific
programming instructions.
Dedicated/User-Defined I/O Bits
The first word in each I/O file contains dedicated Control/Status bits (Bits
0-7) and user-defined I/O bits (Bits 8-15). The minimum SLC input bit
configuration consists of one 16-bit word. The maximum input bit
configuration consists of three 16-bit words. The following tables present
examples of minimum and maximum input bit configurations, and
definitions of the dedicated Control/Status bits.