You can configure this card to condition two UART devices, or two encoders, or to provide an external clock output.
Item Description
494.47 Dual
UART/Encoder/External Clock mezzanine card icon
Type: specifies the type of device used with this card: Encoder, UART, or external clock output.
The external clock selection provides an external clock output (RS-485 differential output) on the front-panel JXA connector located on the Model 494.40 I/O Carrier. The external clock output can be used to synchronize subsystems (such as data acquisition) to the controller clocks.
Encoder Properties Note:
The following settings only appear if Encoder was selected from the Type menu.
Application Attribute: Not applicable
Mode : specifies the type of encoder used with this card: Gurley (Teledyne), Incremental/Velocity, SSI (Temposonics R), PWM (Temposonics G).
Debounce Filter: specifies the filtering applied to the input signal. Debounce filtering is typically used clean up the shape of the pulse in situations where there are long cable runs or signals with long rise and fall times (for example, a proximity switch counting gear teeth) with noise riding on the signal.
The default setting (40 ns) works for most applications.
Incremental/velocity encoder signals (especially single-ended counter types) are somewhat more susceptible to noise. If the noise results in extra counts, you may need a longer debounce time setting. If the
debounce setting is too long, the debounce filter will filter out the encoder signal.
SSI (Temposonics R) /Gurley (Teledyne) encoders only:
Resolution (bits): this setting must match the number of bits in the encoder’s data stream. Gurley=16 or 17 bits; SSI=1-32 bits.
Baud Rate: specifies the communications clock rate between the processor and the encoder.
Type: specifies the type of encoding (Binary or Gray Scale) used by the encoder.
Encoder icon Application Attribute: Not applicable
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For Incremental/Velocity and PWM (Temposonics G) encoders, selections include Quadrature or Counter (single ended).
For SSI (Temposonics R) and Gurley (Teledyne) encoders, selections include Signed or Unsigned.
For rotary devices, this setting is user preference. When “Turns Counting” (see below) is enabled, the “Signed/Unsigned” setting only affects the range of the initial reading at power up.
For linear devices, the “Signed/Unsigned” selection is based on the behavior described below.
l Signed–the reading from the device represents both positive and negative values. For example, -180 to +180 degrees for a rotary device, -100mm to +100mm for a linear device.
l Unsigned–the reading from the device represents only positive values. For example, 0 to 360 degrees for a rotary device, 0mm to +200mm for a linear device.
Encoder icon Mode
Selections include Rotary or Linear.
Turns Counting (rotary encoders only): (only available for SSI (Temposonics R) and Gurley (Teledyne) settings)
True: the firmware adds an offset to the signal that reflects the number of turns (for each turn, the firmware adds 360 degrees to the encoder output signal.) For example, if the device powers up at 0 degrees and rotates 1.5 positive revolutions, the encoder channel will read 540 degrees.
False: the encoder channel represents the actual reading from the device. Each time the encoder signal reaches 360 degrees, the encoder output resets to zero. For example, if the device powers up at 0 degrees and is rotated 1.5 positive rotations, the encoder channel will read 180 degrees.
Encoder icon AutoZero on Index Pulse
(only available for the Incremental/Velocity setting):
True: the encoder position signal is zeroed each time an index pulse is read.
False (default): after a maximum count of 231, the encoder position signal resets to -231 and continuously counts up to 231 and resets.
HWI Hardware Settings
86 MTS Series 793 Utility Software
Item Description
Analog Input icons Each encoder input includes two analog-input icons:
Analog Inputs (position) with encoder icons–allow you to set input filtering for the encoder position signals.
Analog Input (velocity) icons–allow you to set input filtering for the velocity signal derived (by firmware) from the encoder’s position signal.
Connector: the connector number for that input.
Name: Describes this resource as it will appear in Station Builder resource lists when opened against an .hwi file.
Note:
Changing this name may invalidate existing station configurations.
Application Attribute: Not applicable
Input Filter Settings:
Filter Type: Used to select the type of digital filter used to filter the input signal. Filter selections include: Disabled, Bessel, Butterworth, and Elliptical. (Default=Bessel, 300 Hz.)
Filter: This is the frequency where the filter, selected in the Filter Type box, attenuates the signal by 3 dB.
Low frequency limit = >0 Hz (A setting of 0 disables the filter.) High frequency limit = 1/2 the system rate.
Important:
Rotary SSI/Gurley devices with Turns Counting = False: filtering may be undesirable because as the signal is filtered, the angle step that occurs every 360 degrees causes ringing due to the high- frequency content of the step. Filtering occurs normally if the encoder is operated in a range that does not include the angle step. UART Serial Comm icon Note:
Only appears when UART is selected as the device type.
Connector: the connector that joins the resource to the chassis.
Name: describes this resource as it will appear in Station Builder resource lists when opened against an .hwi file.
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Changing this name may invalidate existing station configurations.
Baud Rate: select the baud rate for the serial device.
Type: select the type of device (2-wire or 4-wire). This setting defines which pins are used and how the system communicates with the UART device.
Note:
Model 409 Temperature Controllers are 2-wire devices; Model 494.05 Handsets are 4-wire devices.
Application Attribute: Not applicable External Clock icon Note:
Only appears when external clock is selected as the device type.
Name: Describes this resource.
Note:
Changing this name may invalidate existing station configurations.
Output Clock Rate: enter the frequency (Hz) for the clock output.
Application Attribute: Not applicable
SSI/Gurley Encoder Application Settings
Application
Encoder Settings
Type = Signed Type = Unsigned
Physical Zero Position at Minimum or Maximum Stroke (device dependent)
N/A
Physical Zero Position at Mid Stroke (device dependent) N/A
HWI Hardware Settings
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Note:
The graphs shown above represent a 12-bit linear device.
Application Encoder Signal
Range Encoder Settings
Power-up Signal range Operating Signal range Type Turns Counting Position Filter Position-Limited Rotation
Power-up signal range: 0 to 360 degrees
Unsigned True Yes
Unlimited Rotation
Operating-signal range: 0 to 360 degrees
Unsigned False See Note
Position-Limited Rotation
Power-up signal range: -180 to +180 degrees
Signed True Yes
Unlimited Rotation
Operating-signal range: -180 to +180 degrees
Signed False See Note
Note:
Rotary SSI/Gurley devices with Turns Counting = False: filtering may be undesirable because as the signal is filtered, the angle step that occurs every 360 degrees causes ringing due to the high-frequency content of the step. Filtering occurs normally if the encoder is operated in a range that does not include the angle step.