Sampler

• Purpose
• Parameters
• Associated Data

• 
  

• There is a delay when using an external encoder.
  The delay is five cycles:
       2 cycles to read the encoder from the AKD via EtherCAT,
       1 cycle for computing,
       2 cycles for sending the new position set point to the AKD).
  This lag error is speed proportional (5 cycles * speed).
  A Phaser block can be used to compensate for this lag.

Purpose

Click to view the Purpose of Samplers

The sampler block is used to periodically sample and place into a pipe some output of a source object. (Figure 1)

Example: The sampled output might be the POSITION or SPEED of the source object measured by a resolver, an encoder, or some other types of sensor.

• The sampler implements a logical connection between an external master (source object outside the KAS system) and one or more pipes.
• This is for slaving the motion of the KAS system to the external master by placing the sampled values into the pipes.

Figure 1: Example: Sampler Parameters

Figure 2 illustrates the concept.

The Sampler feeds motion trajectory data derived from an encoder (or resolver) coupled to the remote machine into the Pipe Network.

Figure 2: Example: Sampler Pipe Block Used to Track an External Master

Parameters

Click to view Parameters for Samplers

Parameter	Range	Unit	Description
SamplingPeriod	0.25 to 31,557,600,000.0	Millisecond	Period that the device is sampled, expressed in milliseconds. Figure 3: Example: Sampler Period
Mode	See Description.	N/A	Sampled output can be either Position or Speed. 1 = Position Mode. 2 = Speed Mode. Figure 4: Sampler Mode Position Figure 5: Sampler Mode Speed
InputModuloPosition	0 to 1.0x10300	User units	Period of the input signal. When used to track the feedback value of an EtherCAT device, the value of InputModuloPosition depends on the EtherCAT device used as an Input Source for this Pipe Block. AKD: This should be set equal to 232 (4294967296.0). AKD2G: This should be set based on the feed constant value assigned in the EtherCAT object 0x60E4 subindex 1-5. 0 (zero) indicates the input signal does not use the modulo operation. See Modulo Affects on the Signal Scaling.
OutputModuloPosition	0 to 1.0x10300	User units	Period of the output signal. 0 (zero) indicates the output signal does not use the modulo operation. See Modulo Affects on the Signal Scaling.

Modulo Affects on the Signal Scaling

This table lists how the values of InputModuloPosition and OutputModuloPosition affects the scaling of the signal.

InputModuloPosition Value	OutputModuloPosition Value	Scaling Effect	Rollover Effect
Non-zero	Non-zero	Output signal = (Input signal) x (OutputModuloPosition / InputModuloPosition)	Output signal rolls over at OutputModuloPosition.
0 (zero)	0 (zero)	Output signal = Input signal	Output signal does not roll over.
Non-zero	0 (zero)	Output signal = Input signal	Output signal rolls over at OutputModuloPosition.
0 (zero)	Non-zero	Output signal = Input signal	Output signal rolls over at InputModuloPosition.

Associated Data

• OutputValue: Output value of the data flows.
• IsReady: Boolean set to TRUE when the pipe block is ready.