FAQ

The PE is important for the safety of the person operating the equipment and safe operation of the devices. All grounds should have the same reference potential level between all the components in the system. This also increases performance by reducing the noise level in the system.

Check voltage ground connectivity with a digital voltmeter, after ensuring that all the connections are secure and well established with proper wiring according to the product’s schematics.

No

Minimum: 1 minute
Recommended: several minutes
The internal capacitance is discharged during this time.

CE and UL

Improper grounding: Can result in excessive voltage drop, drive failure or personal injury. Improper power supplied: Shorting terminals or improper isolation. Grounding the reference neutral of an AC input could result in drive failure and injury.

Proper grounding, cable shielding, proper connections.

False.

When an amplifier is connected to the power supply and the power is activated, initial high level in-rush current can occur. This problem is solved by using negative thermal voltage transistors (NTCs).

Advanced unipolar with fast technology.

Resistor sensing on low side power bridges, hall effect sensors on motor phases.

For drive protection (under- and overvoltage) and current GS control loop.

Short protection: Phase-phase, phase-ground, phase-VP+ Under/overvoltage, temperature protection.

To dissipate energy that is absorbed into the system, without harming the stage up to a certain rated level. This can occur during rapid deceleration of a high internal load.

Passing current through the coil of a starter, creating a magnetic field perpendicular to the rotor’s field.

The ability to drive and move a motor based on an electrical input current. Two phases of the brush motor have voltage applied to the brushes creating a magnetic field to repeatedly turn the rotor 90°.

BEMF (Back Electromotive Force) is the energy voltage developed on the system during rotation as a result of the inherent motor characteristic properties. This is always less than or equal to the rotation speed on a torque-speed curve.

Advantage: They are simple motors where no commutation is required.
Disadvantage: They require maintenance and are not very efficient.

Six-step and trapezoidal commutation are the same methods with different names. Elmo uses sine commutation.

About 13%–14%

Very minimal, less than 1% of a sinusoidal motor.
13%–14% of a trapezoidal motor.

An AC brushless motor is more accurate (mainly regarding velocity) and requires almost no maintenance. However, the drive electronics are more expensive and more complex.

Digital Halls, incremental encoder, a combination of digital halls and an incremental encoder, and absolute serial sensors.

Reference it according to the product matrix. “R” is for Resolver, and so on. It is usually the last product code of the catalog number.

They assist in commutation of the motor for electrical cycle reference. The hall sensors give the location of the rotor to a tolerance of ±30 electrical degrees.

Six states

There are two illegal states in Elmo drives. Those states are ‘111’ and ‘000’

Mainly for noise immunity.

No, only phase correction. Namely offset correction of the absolute hall’s zero with respect to the motor’s electrical zero.

The amount of current carrying ability of the wire with respect to its diameter. For example: If you have a thinner cable you can’t transfer so much current. If you have a larger cable diameter you can transfer more current. When the AWG is high the ampacity is low, and when the AWG is low the ampacity is high.

No it is false

They should be as wide as possible (low AWG), not twisted but shielded. Ground the outside of the motor.

Low DC voltage drives (less than 200 VDC). The isolated transformer provides isolation between the logic and the power stages of the drive.

Twisted and shielded cable. In case of using isolation the PE should be shorted to the power supply PR. In case of DC offline drives (when an isolated transformer is not essential, PE should not be shorted with the PR of the PS.

Add capacitance; make the wires as wide as possible. This is in order to prevent high voltage drops across the cable edges.

It is for the logic in the event of power loss to the driver. The PE is connected to ground via the PR.

200 mA

To reduce the noise level and obtain a better signal integrity.

20 MHz.

±10 VDC

14 bit. We oversample the 12 bit ADC to reach 14bit resolution.

5 V or 24 V depending on the device.
20 mA

5 V

Motor Off, MO=0

Yes

To smooth the velocity corners (as jerk). The maximum value is 100 msec.

PTP, PVT, PT, Jog, idle

MO=0    PX=0    MO=1    PA=0    PV=1000     PA=1000   BG

MO=0, UM=4     YA[4]=0    EF[2]=<value for noise>    MO=1

2 x 2¹³ = 16,384

Matching phase offset properly, amplitude matching and lissajous creation of the analog input.

No in the case of single pole resolver, it is absolute. In other cases it does require auto phasing.

When an analog signal is channeled into the main feedback, it is emulated to the auxiliary feedback output. This can be converted to a digital signal.

You must use a line driver to buffer out the signal externally to the WHI

Differential is between a ± valve (i.e. ±5 V) and single end is a + valve with respect to zero (i.e. +5 V to 0 V). Differential is better for noise immunity.

It is a generator based on the voltage from the motor. It drifts around 0.

Yes

Possible drive failure, unsafe conditions, sparks or arching.

Keep the wires as short as possible, with proper shielding and grounding. Also separate them as far as possible (motor and feedback, hot and cold)

No

Yes

True

One scenario is for a switch mode power supply over a long distance placed near the power supply leads. Capacitance could be in some cases be a replacement for a “shunt” resistor. In some cases it is not sufficient and a shunt regulator is recommended.

Common node, star connection (not daisy chain)

Both ends to eliminate voltage drop to the PE system frame with one open hole end and the other through proper connection shielding.

All of them, as that is the point of proper grounding. I.e., the power supply, drive and controller.

When there is noise in the lines to the motor phases. Do not wrap the ground wire.

If the motor’s inductance is too low or when the current ripple is too high.

PIP is easier to tune, can use feed forward and gain scheduling is also possible.

Current gain tuning, commutation, digital inputs and outputs, velocity gain tuning and position tuning

RS232 – up to 57,600 bps
CAN bus – up to 1 Mbps

To obtain the proper commutation angle each time the drive is switched on. This is done when no absolute sensor is available.

Set KP=0 and KI=0. Set a range of movement (±1000 counts) and a velocity (±1000 counts/second), and observe the velocity command with respect to the actual velocity. Double KP until there is a 25% overshoot, decrease KP by 75% to start KI and obtain the rise time. Take KP/Rise time and start KI. Increase until the velocity command and the velocity track well.

Signal Oscillation, high overshoot and undershoot.

Slightly lower the speed of travel. If the saturation is large, decrease it significantly.

To stabilize the velocity during steady state motion (0 velocity error).

The difference between the commanded position with respect to the position feedback, i.e., PCMD-Px.

Less wiring, management and monitoring of amplifier status. Overall reduced cost of ownership after everything is assembled. Less EMI.

To maintain the line impedance and noise immunity.

About 5 kbps x 100 = 200 µs

The storage and execution of Elmo commands on PDO2.

0x35D

Node ID 47 sends an emergency message.

It pings/polls the CAN bus for the status of Node IDs

Confirmed messages, usually SDOs

0x753 – an error message

Time difference counter (counter from a set point with respect to the time declare)

Floating will yield a decimal

1, it rounds down

The motor must be off.

TC (internal)
Analog (external)
PWM (external)

Profiler, external analog command, follower on external encoder

Smooth factor is the sinusoidal adjustment of the acceleration.

HL[2] is the limitation of VH[2] so VH[2] = HL[2]/2

No
100% only since it enables the highest possible resolution.

PM=1 Use the profiler (acc + dec + SF)
PM=0 Bypass the profiler – gives step response to the system.

SF=50.

ECAM, 32 KB of memory.

Synchronize motion with an external axis.

Using two encoders as an input to close the position and commutate the motor. For example, it is used when closing the position on  the linear encoder of a ballscrew stage and commutation for the motor on the end.

The position reference generator is a software command, external position reference and stop manager.
Point-to-point, jog, PT, PVT, idle

yes

Moving at a constant velocity. Position unit mode.

This involves a separate input through the Elmo auxiliary encoder input. Each pulse advances the position by one count and gives the direction. The width of the pulse determines its speed.

A textile curtain machine rotating a drum while outputting positions to 50 separate motors in order to sew a certain pattern.

For proper machine flow control and to react to external situations that may take place in the machine.

CPU loads. Servo is the highest priority, communication is higher than the user program, and automatic routines can interrupt the program.

With tdif commands, TM or tick-tock

No, we must use “while” infinite loop

Wait execute wait
Infinite loop waiting for a condition
Use autoroutines

Until waits for a condition to be true.
“until (0)” will never end

Float, integer, functions, global functions, operands (conditional, rational, mathematical)

Step by step, break points

An expression or iteration that filters or executes a specified routine when the conditions are met.

The maestro is a multi-axis motion controller that is based on an embedded Linux OS

The Maestro Kernel contains modifications that enable servo control.

This Kernel is called the Multi Axis Firmware.

It is the name of the Maestro Kernel modifications for a Multi Axis motion control.

 Each firmware has its own version number.

There are 2 Maestro family types:

• The Gold Maestro (GMAS), which is the first generation
• The Platinum Maestro (PMAS), which is the second generation, with enhanced and advanced HW

Both family types have a harsh environment version. The PMAS family also has a PMAS IO, which is a derivative version that contains extended HW. This extension includes IOs and serial communication channels.

Yes.

The Maestro implementation of motion control is in accordance with the PLCopen standard.

No.

With EtherCAT, the Maestro can support other vendors’ devices, on condition that these devices are supported by the EtherCAT standard.

These fieldbus types are very common. They support both DS402 and the PLCopen standard.

DS402 is a protocol that implements a data transfer method, which executes servo control according to the PLCopen standard. The Maestro supports this protocol.

The Maestro runs a user program that is a dedicated SW application, implemented by user, in order to perform its machine / system motions.

There are 2 main options for the user to write and run a program in the Maestro:

 IPC and RPC

IPC stands for Inter-Process-Communication. In the Maestro, there is a program that resides and runs in the Maestro user space section, and interacts with the Maestro Firmware to execute the motion part of the user program.

RPC stands for Remote-Procedure-Call. It means that there is a user program which runs on a Host Peripheral computer and interacts with the Maestro remotely via TCP/IP communication

The most common RPC platform is the win32 OS platform.

Addition platforms are Win64 and Linux OS(x32, x64)

Elmo also supports Embedded OS such as VxWorks OS platforms.

The user program interacts with the Maestro by integrating the ELMO Library with the user program. The ELMO Library is responsible for the interaction and data transfer between user programs and the Maestro FW.

There are several ways:

* As an RPC program

* Via TCP/UDP channel. In this case, a MESTRO IPC program is required to run and open a

socket (UDP, or TCP, or both, depending on the application design). Also, the

host computer needs to have a program running with an open socket containing the

appropriate IP address and port, so that the data can be transferred between the Maestro and the host computer

programs.

* Via ModBus over TCP.

* Via Ethernet/IP protocol.

By calling the ELMO Library APIs. For example, a designated function which performs the desired motion within the user program.

* For IPC: MDS (Maestro Developing Studio) is an ELMO Customized Eclipse IDE for developing IPC programs.

* For RPC: the default environment is Visual Studio for Winx32 /Winx64 operating systems.

* For RPC (not Windows): ELMO multiplatform library allows you to develop in C and C++

on a variety of OS platforms.

* Codesys IDE allows PLC programmers to write in IEC languages.

By default it is not, but it is possible to set it to be synchronized and on the cycle rate of the EtherCAT network clock.

       Single axis control such as accurate PTP, Jogging, ECAM, Splines, and PVT  

       Trajectory motion, Synchronized Group Motion (linear, Cyclic, Polynomic)

       Synchronized Kinematics configuration such as Cartesian, Delta, and SCARA

       Robots, changing target ‘on the fly‘, IOs, DS402 Homing, etc…

No, it is not possible.

The system configuration and topology (e.g. CANbus or EtherCAT networks) of the drives must be completed before programming with a Maestro user program.

Currently, the fastest cycle rate for a Platinum Maestro is 250uSec for 16 axes

 The fastest cycle rate for the Gold Maestro is 250uSec for 4 drives, and 1mSec for 16 axes.

The maximum number of axes in a synchronized group is 16.

The Maestro can work with up to 100 axes.

Maestro provides the optimal profiler performance of the ELMO drives.

Currently, there are several ways of implementing it. 

• Develop a GUI as an RPC program (such as a .NET framework with a GUI that calls the ELMO APIs )
• Develop a GUI by a Codesys program visualization which integrates as part of the Codesys program that runs on the Maestro
• Develop a GUI using any other HMI program (including Codsys visual) which runs independently and interacts with a Maestro IPC running program via UDP/TCP/MODBUS/EthernetIP/Serial communication

The Codesys is running in the Maestro user space and interacts with the Multi Axis Firmware, in the same way as an IPC program.

For IPC programs, use C/C++.

RPC programs can be written in C , C++, or C# (when running on Windows OS)

Codesys programs support the IEC languages: ST, LD, FBD, CFC, and SFC.

Some of them are, and some are not.

• Programming with MDS is free of charge.
• Regarding RPC programming, it depends on whether programming IDE has a fee or not. For example, writing a Windows program using Visual Studio may have a fee according to Microsoft policy.
• Regarding Codesys programming, there is a license fee for using it, there are 2 types of licenses, one with a visualization option and one without. The payment is made when ordering a Maestro, with the corresponding part number, which contains the desired Codesys License.

Use a linear analog feedback (a potentiometer for example) and connect it to the feedback input of the amplifier. Connect your position command to the reference input. Then convert the amplifier to Current Mode and adjust the gain for best position accuracy.

PWM and Direction is a digital method of transferring analog information. It is mainly useful when optical isolation is required between the source of the command and the amplifier. Step and Direction is a position control method and it requires a position controller on top of the analog amplifier.

The PWM amplifier requires a unipolar power supply. This means that the bipolar power supply is wasted when used with a PWM drive. If you insist on using your bipolar supply with a PWM amplifier, pay special attention to the circuit common connection and common mode issues. You may be required to isolate your reference command.

Higher voltage and lower inductance is preferred for servo performance with a tachogenerator.

Despite the fact that the voice coil motor is a “brushless drive”, you can use a standard brush drive with it.

There are many optical encoders in the market that provide the “Hall sensor signal” through optical channels. If your encoder is one of these, just treat these outputs as if they are Hall sensors and connect them to what is defined in the amplifier literature as Hall inputs.

Yes you can. Elmo has achieved 200:1 speed regulation with Hall sensor speed control using inexpensive analog drives.

A good trapezoidal drive is a less expensive drive and it will satisfy most applications, especially the point-to-point ones. The sinusoidal drive is more expensive and is required for better low speed smoothness.

The resolver withstands a harsh environment better but its R/D circuit is expensive and it is also bandwidth limited. The optical encoder is more fragile than the Resolver but it performs better for servo applications and is also less expensive.

Although digital drives are more expensive, they are friendlier than analog ones and have excellent long-term stability. Also, their serviceability is far easier than analog drives.