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Rockwell Automation Publication 1734-UM007E-EN-P - October 2015
Chapter 4
Set and Operate Your Module
SSI Word Delay Time
This is the time between successive SSI words that are transmitted by the SSI sensor to
the module. The 1734-SSI module features a wide selection of delay times ranging
from 16…64,535
μ
s. The module default delay time is 64
μ
s.
Refer to your SSI sensor data sheet for the recommended delay time. If the sensor
manufacturer specifies a value called monoflop time, use that value for the SSI word
delay time setting.
SSI Word Filter Control
The number of successive, equal SSI data words received by the module from the SSI
sensor in order to update the real-time present SSI data word. Max = 5 successive
equal values, High = 4, Med = 3, Low = 2, and Off = the module produces a SSI data
word each time a new value is available from the SSI sensor, without the previous
value comparison.
Adjust the SSI Word Filter Control value when using SSI sensors with the Position
Forming time < 0.5 ms, so that you can see SSI sensor data change as the sensor is in
motion.
Note that changing the default value of 5 (Max) for this parameter is done at the
expense of reporting accurate sensor data in an electrically noisy environment.
Data Standardization
You can remove bits from the right side of the displayed SSI present value word by
setting Data Standardization to ON.
This feature can be used as a divide by a power of two, or for data masking. Enter the
number of bits you wish to remove in the Trailing Bits parameter (discussed below).
The default setting for Data Standardization is OFF.
Trailing Bits
The number of bits removed from the displayed SSI present value word if Data
Standardization is ON. The range is 0…16 bits, and the default value is 0.
Sensor Resolution
The number of steps per revolution for a rotary sensor, or total number of steps per
stroke for a linear or optical transducer.
The Sensor Resolution value is not used by the module and is not needed for proper
module operation with your SSI sensor.
The Sensor Resolution value can be passed to the network master for processing if
desired.
The range is 1…65,535 steps and the default value is 1.
Sensor Cycles
The total number of revolutions for a rotary sensor. If you are using a linear or optical
transducer, the value you should enter for Sensor Cycles is most likely equal to one.
Like the Sensor Resolution parameter, the Sensor Cycle value is not used by the
module and is not needed for proper module operation with your SSI sensor. Pass the
value to the master if needed.
The range is 1…65,535 steps and the default value is 1.
Data Latch
Define an edge of the sourcing I1 input for storing a sensor position. The choices are
the falling edge of I1 (Off-to-ON), rising edge (On-to-OFF), or both falling edge and
rising edge.
The default value for Data Latch is OFF. For operation details, see operating feature of
Data Latch.
Comparator 1 and
Comparator 2 Control
You can compare the incoming SSI sensor count to a stored value, and the module
provides notification of the event when the present sensor value equals or exceeds the
stored value. The module stores two separate comparator values (1 and 2), governed
by separate comparator control values (1 and 2). Using the comparator control
parameter, you can set the module to flag the event on an increasing, decreasing, or
both (increasing and decreasing) sensor count.
The default setting for both of the Comparator 1 and Comparator 2 Control values is
OFF.
For operation details, see operating features of Comparator 1 and Comparator 2
Control.
Comparator 1 and
Comparator 2 Value
Enter your comparator value into these parameters. Comparator values can be
obtained by moving your SSI sensor to the position of interest and reading the present
SSI value.
Value
Definition