Rockwell Automation 1732E-OB8M8SR EtherNet/IP Dual Port 8-Point SOE Input and Scheduled Output Modules UM - Manual (Page 22)

12 Rockwell Automation Publication 1732E-UM003B-EN-E - March 2014
Chapter 2 Module Overview and Features
Individual schedules are created in the controller, stored in the output image table
for the module, and sent over the backplane to the Scheduled Output module.
The schedule specifies a sequence count, the output point to be associated with
the schedule, the time at which an output value should be applied to the physical
output point, and the value to be applied at the scheduled time. The I/O module
receives and stores the schedule. The CIPSync time of each schedule is monitored
by the module. When a schedule has expired, that is the current time, matches the
scheduled timestamp, the output value is then applied to the corresponding
output bit. Timer hardware in the ASIC is used to optimize the scheduling
algorithm. This hardware also reduces the latency and jitter performance. Status
of each schedule is reported in the output echo connection and reflected in the
input image for the module.
The scheduled output functionality relies on CIPSync time. Unused outputs may
be used as normal outputs and are applied immediately rather than waiting for
the CIPSync time to expire. A mask is sent to the module to indicate which
outputs are to function as normal outputs. The scheduled output module
supports up to 8 outputs that can be individually scheduled. The scheduled
outputs must be between output points 0 and 7. The 1732E-OB8M8SR module
supports up to 16 schedules with two schedules per output. Outputs that are not
“scheduled” are used as normal output points. A mask is used to indicate which
points are scheduled and which points are unscheduled. Jitter performance is less
than 25
µs. All of the scheduling configuration is done through the MAOC
instruction.
If a new schedule as indicated by a change in the sequence count is received by the
I/O module before the current schedule has expired, the current schedule is
overwritten. This mechanism can be used to cancel currently active schedule.
Status bits returned in the output echo connection may be used to determine the
current state of each schedule and to trigger corresponding event tasks.
If a new schedule is sent by the controller and the CIPSync time has already past,
the output is asserted until the CIPSync time has completely wrapped around.
The module does not check for an expired CIPSync time.
High Speed Product Reject
In a control system you can program a scheduled output module, which can
trigger multiple outputs simultaneously or trigger a reject at the precise point a
product is at the reject station.
WARNING: If the time between two schedules is less than the
minimum schedule interval (for example, 100
µs), then deviation occurs.
This means that even though two outputs are scheduled at different
times (for example, time 90 and time 110), they both activate at the
same time (for example, time 90). The minimum schedule interval should
not be set to faster than 100
µs.