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Laser Control modes in ACS products PDMnt CMba/hp with PD option Application Note
June 2014 Document Revision 2
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Laser Control modes in ACS products Table of Contents
Laser Control modes in ACS products Release Date: May 2014 COPYRIGHT © ACS Motion Control Ltd. 2014. All rights reserved. Changes are periodically made to the information in this document. Changes are published as release notes and later incorporated into revisions of this document. No part of this document may be reproduced in any form without prior written permission from ACS Motion Control. TRADEMARKS ACS Motion Control, SPiiPlus, PEG, MARK, ServoBoost, MotionBoost, NetworkBoost and NanoPWN are trademarks of ACS Motion Control Ltd. Windows and Visual Basic are trademarks of Microsoft Corporation. EtherCAT is registered trademark and patented technology, licensed by Beckhoff Automation GmbH, Germany. Any other companies and product names mentioned herein may be the trademarks of their respective owners. www.acsmotioncontrol.com
[email protected] [email protected] NOTICE The information in this document is deemed to be correct at the time of publishing. ACS Motion Control reserves the right to change specifications without notice. ACS Motion Control is not responsible for incidental, consequential, or special damages of any kind in connection with using this document.
Table 1. Revision History Date
January 2014 May 2014
Revision
01 02
Description
Initial release for tests. Implementation of remarks from tests and Application Engineers. Conversion to new template Complies with FW version 2.25
Table of Contents Table of Contents ........................................................................................................2 1
2
Product overview...................................................................................................4 1.1
Minimal requirements for laser control support - Products’ configuration................4
1.1
Assigning an axis to be a P/D or a laser control axis ...........................................4
1.2
Laser interface signals....................................................................................4
1.3
Laser operation .............................................................................................4
1.4
EtherCAT network considerations.....................................................................4
1.5
Laser control: supported modes of operations...................................................5
1.6
What is addressed in this application note? .......................................................5
Ordering options ...................................................................................................5 2.1
Naming........................................................................................................5
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Laser Control modes in ACS products Table of Contents
2.2
Ordering ......................................................................................................5
3
Installation instructions ..........................................................................................5
4
Laser electrical interface .........................................................................................7 4.1
Signal polarity ..............................................................................................7
4.2
Enable laser operation (ENA output signal)........................................................7
4.3
Laser reported faults (FLT input signal).............................................................7
5
Laser control modes of operation .............................................................................8
6
Software specification ............................................................................................8 6.1
Overview .....................................................................................................8
6.2
Real time operation .......................................................................................8
6.3
Initialization .................................................................................................9 6.3.1
PFGINIT function ...............................................................................9
6.4
Start/stop pulse generation process .................................................................9
6.5
Duty cycle or Frequency update.....................................................................10
6.6
6.5.1
PFGPAR .......................................................................................... 10
6.5.2
Frequency or duty cycle update as function of actual motion ..................10
6.5.3
Reading laser’s Status ...................................................................... 11
Sample program ......................................................................................... 11
7
Support tools specification .................................................................................... 12
8
System performance specification .......................................................................... 12
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Laser Control modes in ACS products Product overview
1
Product overview
Laser control is provided as a programmable mode of P/D supporting products, implemented in 2 ACS products: PDMnt and CMba/hp with PD option.
1.1 Minimal requirements for laser control support Products’ configuration In order to support laser modes, the above standard products have to contain a specific HW (a programmable device, FPGA revision 4 or later) revision which can be verified by system information (#SI) command from the MMI terminal, and must have firmware version 2.25.
1.1 Assigning an axis to be a P/D or a laser control axis Products which support laser control, support assignment of each of the 4 axes to be either a P/D or a laser-control interface. Mode of operation selection (P/D or Laser) as well as setting of laser operating modes and parameters is done by ACSPL+ commands.
1.2 Laser interface signals Three interfaces are usually used to control a laser: an electrical stream of pulses (input to a laser), an electrical enabling signal (input to a laser), and a safety fault signal (output from a laser). Additional control signals may be programmed to support laser operation, as function of their availability in the selected ACS drive: digital outputs and inputs are an example.
1.3 Laser operation When an axis is being configured for laser control, the corresponding interface generates digitally shaped pulses as function of programmed motion trajectories, as generated by the MPU. The axis benefits from all standard supporting features provided by ACS firmware and ACSPL+ as such it is treated as a regular network axis, that has to be enable (by ENABLE ACSPL+ command) in order to generate pulses and which can be configured only while disabled. The ACSPL+ ENABLE command also results in a physical output signal (activation of ENA+/ENA- to a current flow state) which may be used by the laser controller as an enabling and/or a safety signal. In addition, the user application responds to the ‘fault’ (FLT+/FLT-) electrical interface input by stopping the application from running, disabling the generated laser-control pulses, and deactivating (no current state) the electrical Enable output signal. The ‘fault’ signal can be used by the laser controller as a safety signal to perform the above activities.
1.4 EtherCAT network considerations In a similar way to a P/D interface, a laser control interface is considered a ACS EtherCAT network axis. This has to be accounted for when selecting and ordering an ACS master. The laser supporting products (PDMnt, and SPiiPlusCMbahp with a PD module) consume 4 network axes, regardless of their axes’ assignment as P/D or laser control.
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Laser Control modes in ACS products Ordering options
1.5 Laser control: supported modes of operations Real-time varying duty cycle (=PWM), with a fixed (programmable) frequency Real-time varying frequency with fixed (programmable) positive pulse width (P/D like) Real-time varying frequency with fixed (programmable) duty cycle
1.6 What is addressed in this application note? This application note contains the following information: Installation instructions and reference to relevant ACS products’ guides Description of the Laser control modes’ description How to select P/D and Laser modes How to connect to a laser and where to find relevant information? How to program a laser control interface
2
Ordering options
2.1
Naming
EtherCAT Pulse/Dir interface Module, 4 axes, 8/8 digital I/O, with LC1 Laser control mode
2.2
Ordering
PDMnt-4-08-08-00-00-1L
3
Installation instructions
Laser control is an extension to P/D capabilities, which exist in the 2 ACS products: Refer to PDMnt and CMba/hp installation guides. SPiiPlusCMba/hp
The relevant laser control signals are detailed in CMbahp Product Guide_v2.25.pdf. Refer to J10 pinout and description of signals in the document.
PDMnt
The relevant laser control signals are detailed in PDMnt HW Guide_v2.20.pdf. Refer to J1, J2, J3 and J4 pinout and description of signals in the document.
Up to date guides and documentation can be downloaded by registered users from www.acsmotioncontrol.com/downloads
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Laser Control modes in ACS products Installation instructions
The following signals are used to interface a laser. Interface signals Pulse+/Pulse-
FLT+/FLT-
Description Direction: Output from drive to laser. Electrical interface: RS422. The interface is programmed by ACSPL+ command to be either a P/D or Laser control interface.RS422. In P/D mode: the Dir+/Dir- interfaces are used as part of Pulse/Direction operation. In Laser mode the Dir+/Dir- interfaces are not used (Laser mode operation is selected by ACSPL+). Direction: Input to drive. Electrical interface: Opto isolated 2 terminal input. Refer to installation guides of the respective products for electrical specification and connector’s pinout. Note that Fault signal can be connected in a ‘source’ and a ‘sink’ configuration, as depicted in the drawings below. Laser 24V controller
ACS drive FLT+
Fault
FLT-
DSP
Fault input (Source type) ACS drive FLT+ DSP
Laser 24V controller
FLTFault
Fault input (Sink type) Figure 1 - Fault input Source and Sink Usage: FLT+/FLT- is a laser generated signal, read by ACS software. As function of the laser interface and mode of operation, an interface may be needed in order to adapt the laser-generated fault/safety signal/s to the ACS recognized FLT+/FLT- interface. ENA+/ENA-
Direction: Output from drive. Usage: An electrical operation-reflecting signal, controlled by ACSPL+ application software. The ACSPL+ ENABLE command results in a physical output signal (activation of ENA+/ENA- to a current flow state) which may be used by the laser controller as an enabling and/or a safety signal. Electrical interface: Opto-isolated 2 line interface. Refer to installation guides of the respective products for electrical specification and connector’s pinout. Note that Enable signal can be connected in a ‘source’ and a ‘sink’ configuration, as depicted in the drawings below.
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Laser Control modes in ACS products Laser electrical interface
5/24V DC supply + -
ACS drive ENA+
Laser controller
ENA-
DSP
Enable output (Source type) 5/24V DC supply - +
ACS drive ENA+
DSP
Laser controller
ENA-
Enable output (Sink type) Figure 2 – Enable output Source and Sink
4
Laser electrical interface
4.1
Signal polarity
In P/D mode the Pulse (see interface signals’ description above) signal polarity by default (and in DISABLE state) is ‘high’ and the pulses are negative. In Laser mode the Pulse signal polarity by default (and in DISABLE state) is ‘low’ and the pulses are positive.
4.2
Enable laser operation (ENA output signal)
In order to avoid undesired transients and faulty signals at the output interface, mode setting has been performed while the axis while the laser axis is in a disable state, following an ACSPL+ DISABLE command. Specification of the ENA+/ENA- signal is found in this application note and in the products’ user guides.
4.3
Laser reported faults (FLT input signal)
A fault signal received from the laser causes the laser controller to enter a disabled mode, and stops immediately generation of pulses from the Pulse+/Pulse- interface as it enters it default state. Specification of the FLT+/FLT- signal is found in this application note and in the products’ user guides.
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Laser Control modes in ACS products Laser control modes of operation
5
Laser control modes of operation
Programmable fixed frequency with controlled real-time duty cycle This is similar to PWM control, where duty cycle is changed in real time. Frequency can be modified, but not in real time. Frequency is set in the range of 8.94Hz to 1,181,102Hz. Refer to Table 3for parameter settings and resolutions.
Real-time Controlled frequency with Programmable fixed positive pulse width In this mode the frequency varies in real time as function of motion ( 8.94Hz to 1,181,102Hz) while a fixed-length positive pulse is generated. Refer to Table 3 - Laser control pulse parameters for parameter settings and resolutions. Controlled frequency with fixed duty cycle In this mode the frequency varies in real time as function of motion (8.94Hz to 1,181,102Hz) while a fixed (programmable) duty cycle pulse is generated. Refer to Table 3 for parameter settings and resolutions.
6
Software specification
FW support of the laser control mode consists of the following: Addition of a new ‘laser mode’ configuration command, which defines an axis to be a P/D or a laser output. New functions which determine the laser’s mode and set the relevant parameters. New functions which define the variable(s) that the laser mode tracks.
6.1
Overview
Laser Control is supported by the new revision of PDMnt and of SPiiPlusCMba/hp. PDMnt is a standalone network node, controlled by an ACS master. SPiiPlusCMba/hp is an ACS control module, and when ordered with P/D option for laser control, the unit includes a network master plus two network slaves (Servo Processor and P/D Module). The products have none of one internal Laser control unit, capable of generating PWM pulses to control laser. The laser control mode and its initial parameters are initialized by the ACSPL+ function PFGINIT. The pulse generation is activated by ENABLE and deactivated by DISABLE commands. The pulse parameters, like frequency or duty cycle, can be dynamically changed (depending on the operation mode) by ACSPL+ program.
6.2
Real time operation
In order to change pulse parameters constantly and in real-time, a dedicated ACSPL+ buffer should be allocated. See detailed explanation below. Several Laser Control units can be initialized and activated simultaneously.
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Laser Control modes in ACS products Software specification
6.3 6.3.1
Initialization PFGINIT function
The function initializes one of the four Laser Control units and sets it to one of the operation modes, and sets initial values for the interface’s internal registers. The selection of Laser Control unit is determined by the axis argument. The Laser Control interface can only be initialized if the corresponding axis is disabled. The function returns an error if the specified axis is enabled while an initialization function is generated.
Syntax int PFGINIT (axis, mode, freq, width, duty_cycle)
Arguments Arguments
axis
mode
Comments Defines 3rd local axis of the P/D product to be of laser interface type. For example, if axes 4,5,6 and 7 were allocated for the PDMnt/ CMba_hp P/D interface, then to initialize laser interface, axis 7 should be specified for this function. Operation mode: 0 - P/D (default mode) 1 – Mode with fixed frequency 2 – Mode with fixed pulse width
3 – Mode with fixed duty cycle freq
Pulse frequency in Hz, range from Table 3 In mode = 1, the frequency is fixed and is not changed during the process. In mode = 2 or 3, the function only sets the initial frequency, while during the process the application can change the frequency using PFGPAR parameter. Pulse Width in milliseconds, range from Table 3 Only has effect in mode = 2.
width duty_cycle
6.4
Duty cycle in percentage, range from 0 to 100% In mode = 1, the function only sets the initial duty cycle, while during the process the application can change the duty cycle using PFGPAR parameter. In mode = 2, the argument has no effect, as duty cycle is automatically calculated by the unit as function of frequency. In mode = 3, the duty cycle is fixed and is not changed during the process.
Start/stop pulse generation process
The function enable (axis) enables a pulse generation process with currently set parameters. If initially frequency or duty cycle is set to zero, then pulse generation is pending till positive value is set. This provides means to synchronize the pulse generation with actual motion, when, for example, frequency or duty cycle is updated as a function of motion reference velocity.
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Laser Control modes in ACS products Software specification
The function disable (axis) stops the pulse generation process.
6.5 6.5.1
Duty cycle or Frequency update PFGPAR
The parameter is used for update of one of the changeable parameters (duty cycle or frequency). The operation mode determines which parameter can be modified by the PFGINIT function: Table 2. PFGINIT Mode and PFGPAR purpose PFGINIT Mode 1 2 3
PFGPAR purpose Duty cycle update Frequency update Frequency update
PFGPAR parameter should be updated by the application during the process. For example, the application can update PFGPAR each controller cycle with a value of desired velocity of actual motion. PFGPAR is a real type array of 64 elements. Each element, which is addresses as PFGPAR(axis), corresponds to the specific axis, the axis represents a specific Laser control interface in PDMnt/ CMba_hp.
6.5.2 Frequency or duty cycle update as function of actual motion The controller provides ability to update a frequency or duty cycle as function of real motion. For example, the frequency can be programmed as function of position or velocity, function of single axis or multi-axes motion. Here are several examples. It is assumed that PFG_AXIS refers to control unit axis, AXIS_X is actually moving axis, LEADING_AXIS – is leading axis of actually moving group of the axes:
1. Pulse frequency is updated as function of a reference velocity change in single-axis motion: PFGPAR(PFG_AXIS) = RVEL(AXIS_X)/XVEL(AXIS_X)*100;
2. Pulse frequency is updated as function of a velocity change in multi-axes motion: PFGPAR(PFG_AXIS) = GVEL(AXIS_X)/XVEL(AXIS_X)*100;
3. Duty cycle is updated as function of position change within the predefined boundaries LOW_POS and HI_POS:
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Laser Control modes in ACS products Software specification
IF FPOS(AXIS_X) >= LOW_POS & FPOS(AXIS_X) <= HI_POS; PFGPAR(PFG_AXIS) = 50; ELSE PFGPAR(PFG_AXIS) = 0
6.5.3
Reading laser’s Status
The axis status is represented through the following commands: Axis status query (?$
) Enabled/disable, operation mode Motor State (MST) variable Only bit Enable has a meaning for PFG module
6.6
Sample program
The Laser is controlled by pulses, generated with the fixed frequency. The duty cycle is variable and is proportional to the velocity #Buffer 1
! Example 1 ! Let assume that PDMnt occupies axes 4 to 7 ! In this case example axis 3 of PDMnt (available axes are 0,1,2,3) is used for controlling a laser ! Declarations global int PFG_AXIS global int PFG_MODE global real PFG_FREQ global real PFG_DC ! Initializations PFG_AXIS = 7 interface PFG_MODE = 1 PFG_FREQ = 1000 PFG_DC = 0
! Axis of PDMnt ! PWM mode ! PWM frequency ! PWM duty cycle
! Internal Laser control ! Mode with fixed frequency ! Initial frequency 1000Hz ! Initial PWM duty cycle
! PFG module initialization PFGINIT (PFG_AXIS, PFG_MODE, PFG_FREQ, 0, PFG_DC)! Laser control interface initialization ENABLE (PFG_AXIS); ! No pulses yet as Duty cycle was initially set to zero stop
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Laser Control modes in ACS products Support tools specification
#Buffer 2
global real AXIS_X actual moves
! Axis_X is an axis which makes
while (1); PFGPAR(PFG_AXIS) = RVEL(AXIS_X)/XVEL(AXIS_X)*100; end
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Support tools specification
Laser control mode is configured and programmed (P/D and Laser selection, as well as Lasermode selection and parameter settings) by ACSPL+ commands only.
8
System performance specification
The motion vector which is being tracked, is reflected at the output port by a varying (frequency and duty cycle) digital pulse-train, thus changing a pulse’s interval (rising to rising edge time) and its duty cycle (ration of logical ‘1’ to interval. Laser control parameters are updated at CTIME intervals, i.e 1kHz, 2kHz and 5kHz, based on firmware processing which translates the motion to interval (in msec) and duty cycle parameters (percentile of varying resolution which is a function of the operating frequency). Laser control pulse parameters The table below lists the maximal and minimal settable frequencies and resulting pulse intervals, along the settable resolutions. Table 3 - Laser control pulse parameters Parameter Maximal frequency
Value 1,181,102 Hz
Minimal frequency
8.94Hz
Pulse width
6.67nsec to 111ms (function of frequency) 0 to 100% NA
Duty cycle range Duty cycle resolution at high frequencies Duty cycle resolution at low frequencies
NA
Drive fault to disable time delay EtherCAT communication lost to disable time delay
<5mS
Resolution A 7kHz resolution is achieved when setting the laser frequency above 1MHz A 1E-6 Hz resolution is achieved when setting the laser to low frequencies The width is controlled at a 6.67ns resolution
The duty cycle is controlled resolution when setting the above 1MHz The duty cycle is controlled resolution when setting the frequencies
at a 0.8% laser frequency at a 0.6E-6 % laser to low
<2mS
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