User manual

Chapter 1 Introduction
9
20 Gear Drive, Plymouth Ind. Park, Terryville, CT 06786
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The remainder of this chapter introduces the many programmable features of the
1761H module. It also introduces backplane programming concepts that allows
you to control the module from the processor.
Programmable Parameters
Programmable parameters are stored in the modules nonvolatile memory. Therefore, you do
not have to configure the module after every power up. Prior to hardware revision H of the
module, the nonvolatile memory was EEPROM. This technology has the advantage of retaining
programmed values for over 100 years. Its disadvantage is its limited number of write cycles,
approximately ten thousand, before the memory will begin to fail.
With revision H, the nonvolatile memory has been changed to battery backed, non-volatile,
static RAM (nvRAM). The battery in the nvRAM is rated for ten years but the nvRAM has an
unlimited number of write cycles. The nvRAM has the additional advantage of significantly
decreasing the time needed to store new parameter values.
Count Direction
This new parameter sets the direction of transducer shaft rotation to increase the position count.
If the transducer cable is wired as specified in this manual and the count direction is set to positive,
the position count will increase with clockwise rotation (looking at the shaft). If the count direction
is set to negative, the position count will increase with counter-clockwise rotation.
hýThe Count Direction default value is positive.
It is also possible to reverse the count direction by reversing four wires in the
transducer cable. If you are installing this module either as a replacement for an
older module or on a machine that is a copy installation of a previous system, you
will probably not need to set this parameter. Once the machine is setup, you can
easily change this parameter if the position is increasing in the wrong direction.
Resolver Type
The Resolver Type parameter is programmable from the backplane and makes Autotech 128
turn transducers compatible with the 1761H module.
hýThe Resolver Type default value is AMCI. The module can then be programmed to
use Autotech transducers.
Transducer Type
This parameter specifies the type of transducer attached to the input channel. The module
needs this information in order to combine the positions of the two resolvers inside the
transducer into one multi-turn position. This parameter is selected by the J2 jumper on the
circuit board and is not programmable from the processor.
When the Resolver Type bit is set to AMCI, the Transducer Type parameter can be set to:
hý100/1,000 Turn transducer (default value)
hý180/1,800 Turn transducer
When the Resolver Type bit is set to Autotech, the Transducer Type parameter is fixed. It
specifies a 128 turn transducer only. The 64 turn transducers are not supported by AMCI.