E23 Error in R88D-HT10 Servo Driver

Question

What is the cause of the E23 error in an R88D-HT10 Servo Driver?

Answer

The 23 error occurs when there is an open phase in the main circuit. An error is detected when a low voltage was detected in the main circuit's input section and lasted longer than 50 ms.

The likely causes of the error are that the main voltage power supply is not being input or there is an open phase in the main circuit. In general, this error is caused by a problem to the power supply input section. Check the main circuit power supply wiring.

Servomotors with Countermeasures against Harmonics

Question

Are there any Servomotors that have countermeasures against harmonics?

Answer

The W-series Servomotors have countermeasures against harmonics.

The W-series Servomotors are equipped with a terminal connection for a DC Reactor, so a DC Reactor can be connected.

OMRON offers Reactors to control harmonics in other Servomotors besides the W-series Servomotors. AC Reactors for Inverters can be used with the Servomotors above.

OMRON AC Reactors for Inverters are listed below, so use the corresponding AC Reactor.

Connect one Reactor per Servo Driver

Servo Driver model	R88D-UP04V:	R88D-UP08V:
Reactor model	3G3IV-PUZBAB2.5A4.2MH	3G3IV-PUZBAB5A2.1MH

Attached Connectors for R88D-U Servo Driver Analog Monitor Output

Question

Is there a cable with attached connectors available for the R88D-U Servo Driver's analog monitor output?

Answer

Yes, there is a cable available. The Analog Monitor Cable for the W-series (R88D-W) Servo Drivers can be used. The Cable's model number is R88A-CMW001S.

3F88L-132 Cam Positioner Replacement Display Unit Issue

Question

When a 3F88L-132 Cam Positioner is replaced with a 3F88L-160 Cam Positioner, can the 3F88L-DP30 RPM Display Unit be used as-is?

Answer

The Cam Output Cable, I/O Terminal, and Resolver can be used as-is, but the Display Unit cannot be used.

The M7E and M7F Digital Display Units are available separately for use as displays.

Select Shape of Motor Shaft if a Reduction Gear is Installed

Question

What shape of motor shaft should be selected if a Reduction Gear is installed on a SMARTSTEP A-series Servomotor?

Answer

Installation

Use a Servomotor with a straight shaft and without a key when installing reduction gears.

Use only the specified combinations of Servomotors and reduction gears. Using a combination that is not specified, or using in combination with another company's reductions gears or Servomotor may result in a reduction in the service life of the motor bearings.

The dimensions of the Servomotor mounting flange on the reduction gears differ for each Servomotor. Do not install reduction gears on a Servomotor other than the one specified.

Install reduction gears on the Servomotor using the following procedure.

1. Remove the rubber cap and check that the set bolt is loose.
2. Insert the Servomotor shaft into the input shaft.
3. Tighten the Servomotor installation bolt according to the tightening torque specified in the following table.


4. Tighten the set bolt according to the tightening torque specified in the following table.

5. After tightening the set bolt, replace the rubber cap.

Using Reduction Gears from Other Companies (Reference Information)

If the system configuration requires that a SMARTSTEP A-series Motor be used in combination with a reduction gear from another company, select the reduction gear so that the loads on the motor shaft (i.e., both the radial and thrust loads) are with the allowable values. Also, control the motor speed and output torque so that the allowable input speed and allowable input torque of the reduction gear is not exceeded

Procedure for Adjusting Gain Manually When Using a Servomotor

Question

What is the procedure for manually adjusting gain when using a Servomotor?

Answer

Perform the following procedures to adjust the gain.

1. Speed Loop Adjustment
   • Speed loop proportional gain
   • Speed loop integral gain (speed loop integral time constant)
   • Current loop command filter



Generally, basic adjustments can be performed using only proportional and integral gain, but vibration may not stop depending on the mechanical system or positioning may be delayed because the gain is low even if the vibration does stop. If this occurs, adjust the current loop filter time constant.



2. Position Loop Adjustment
   • Position loop proportional gain

This adjustment is used with a pulse train input. It is not relevant to an analog input.

Relation between Gain and Response:

1. Speed Loop Adjustment

The following graph shows how the response of the servo system (i.e., frequency characteristics) changes when the speed loop gain and adjustment parameters are changed.





In this graph, the horizontal axis represents the frequency (i.e., movement speed) and the vertical axis represents the strength of the corrective ability (i.e., the ability to have error approach zero).



1. Speed Loop Proportional Gain
   • Response is changed across all frequency ranges.
   • Increasing the gain increases corrective strength and response speed.
   • Increase the level until the mechanical system does not vibrat


2. Speed Loop Integral Gain
   • Response is changed at low frequencies
   • Increasing the gain increases servo lock strength.
   • Increase the level until the mechanical system does not vibrate.
     (With the U Series, decrease the speed loop integral time constant.)
3. Current Command Filter
   • Response is changed at high frequencies.
   • Increasing the filter time constant makes sudden command changes smoother before they are delivered to the current loop.

This adjustment is effective when there is mechanical system resonance and adjustment cannot be performed using only speed loop proportional gain or integral gain.




Adjustment Example 1

• The following figures show a normal adjustment example (if there is no vibration at initial settings).
• Adjustment is performed for proportional gain and then integral gain.




Adjustment Example 2

• The following figures show an example of adjustment when there is a point of large mechanical system resonance in a high frequency range. The conditions are a low gain setting, humming motor, and generating a high-frequency vibration.
• Adjustment is performed for current command filter time constant and then for integral gain. Resonance with the mechanical system can be avoided by increasing the current command filter time constant. Afterwards, perform the adjustment as normal adjustments are performed.




Adjustment Example 3

• The following figures show an example of an adjustment when is a large point of mechanical system resonance in a low frequency range. The conditions are a low gain setting and generating a low-frequency vibration.



Changing Response Using Speed Loop Adjustment

The following figure shows the servo system response (time axis) when the speed loop gain and the adjustment parameters are changed.



• Speed Loop Proportional Gain and Response

• Speed Loop Integral Gain and Response

2. Position Loop Adjustment
   • The position loop is adjusted after the speed loop adjustment has been completed.
   • Response improves when position loop proportional gain is increased as long as overshooting or undershooting does not occur.
   • Position Loop Proportional Gain and Response
   
   • Overshooting and undershooting can be checked by using an oscilloscope to measure the voltage output at the motor speed (NM) terminal.
   • If no measuring equipment is available, check the movement of the motor shaft or mechanical system visually. If there is undershooting, perform positioning when the motor is stopped in the opposite direction of the rotating direction (as in the following figures).
   
   • The amount overshooting and undershooting depends on the rotating speed of the motor. Normally, the amount of overshooting and undershooting increases as the rotating speed increases. Therefore, it is recommended to perform adjustment using the maximum rotating speed.

Countermeasures of Noise for Servo System

Question

What concepts are applied for countermeasures for noise for a Servo System?

Answer
1.Countermeasures for Noise

The following four aspects are important when considering countermeasures for noise.

1-1. Investigate Noise Sources

Devices that cause rapid changes in voltage or current are noise sources.

Generally the larger the signal power, the stronger the noise source becomes.

List the noise sources that surround your Servo System.

1-2. Identify the Noise Transmission Path

Once you know the source, position, type, and characteristic of the noise, you can narrow down the noise transmission paths. For each possible noise transmission path, apply a countermeasure. Start with the most probable path. You can narrow down the noise transmission path by seeing how effective the countermeasure is.

Another method is to use shield boards connected to frame grounds to check the effect of electromagnetic waves, electromagnetic induction, and electrostatic coupling.

1-3. Noise Countermeasures Must Not Be Removed until the End

Even if the countermeasure applied to a noise transmission path was ineffective, do not remove the countermeasure. There may be several noise transmission paths and the countermeasure that you applied may be blocking the second largest noise path.

1-4. Noise Transmission Paths That Are Common in Servo Systems

Leakage current from the motor electrostatic coupling to the frame ground becomes large in Servo Systems and Inverters.

If the current is not absorbed very well, the frame ground potential will become unstable. This increases cases where noise is transmitted to other devices through the frame ground.

2. Actual Noise Countermeasures

Countermeasures for noise transmission paths as well as countermeasures against leakage current are described below.

2-1. Countermeasures for Electrostatic Coupling

2-2. Countermeasures for Conductive Coupling

2-3. Countermeasures for Electromagnetic Induction

2-4. Countermeasure for Electromagnetic Waves

Note:Use a noise filter for an output without a capacitor for the noise filter on the driver output side.

2-5. Countermeasure for Leakage Current


3. Other Noise Countermeasures

If noise-related errors persist even after applying noise countermeasures, try the following measures. They may be effective depending on the model of Position Controller and Servo Driver.

3-1. The Positioning Point Is Offset When Connected to Position Controller with a Pulse Output
Problem:

Noise is superimposed on the command pulse input signal, so the Driver takes the noise as a command signal.

Countermeasures:

Separate the power source.
Use a dedicated power supply for the Controller's pulse output.
It is effective to separate the ground line as well.

Shield the pulse signal.
If positioning is offset even after separating the power source, connect both ends of the command pulse signal line shield (shielded twisted-pair cable) to the frame ground.

Note:
Make sure that the Controller and the Driver are always grounded to 100 Ω or less.
If the grounding is ineffective, it will make the problems worse.

3-2. The Positioning Point Is Offset When Connected to Connect to a Controller with an Analog Output
Problem:

Noise is superimposed on the feedback pulse (encoder signal), so the Controller takes the noise as a feedback pulse.

Countermeasures:

Shield the feedback pulse signal.
Connect both ends (Controller and Driver) of the feedback pulse signal shield (shielded twisted-pair shielded cable) to the frame ground.

Note: Make sure that the Controller and the Driver are always grounded to 100 Ω or less. If the grounding is ineffective, it will make the problems worse.

3-3. The Ground Is Bad
Problem:

If the ground to 100 Ω is bad, noise will be transmitted from ground. If noise persists no matter what countermeasures are used, check the ground potential.

Countermeasures:

Connect to a good ground at 100 Ω or less.

Improve the condition of the ground.
Separate the frame ground of high-power devices and low-power devices.

Float the frame ground line of the Control device and other applicable devices

Cut the shield of the shielded cable.
These countermeasures are for worst case scenarios. If the Servo System is operating in an environment with serious noise problems, it will not operate at full capacity.

Countermeasures of Noise for Servo System

Question

What models of Servomotors with decelerators are used with SMARTSTEP A-series Servo Drivers?

Answer

The Decelerator and Motor for the SMARTSTEP are separate devices. You must attach the Decelerator (sold separately) to a Servomotor with a straight shaft without a key.

Note:The Decelerator used to come attached with the motor, but the SMARTSTEP treats them as separate devices. The Decelerator must be attached by the customer.

Kind of Noise Generated and What Kind of Noise Affects Operation of Servo System

Question

What models of Servomotors with decelerators are used with SMARTSTEP A-series Servo Drivers?

Answer
1. What Is Noise?

Noise is an unexpected random signal. Some noise originates from natural phenomena, such as lightening, but most noise that actually affects the operation of a device is created artificially inside or external to the device. Think of noise as an artificially created signal that travels through a transmission path to another signal line.

2. Types of Noises

Noise Sources

Devices that cause rapid changes in voltage or current are noise sources.

The more rapid the changes, the higher the voltage, and the higher the current, the stronger the noise source becomes.

Note:PWM (pulse width modulation) is a method used to alter the voltage. By switching the voltage ON/OFF at a fast switching frequency, the average voltage can be modified.

3. Transmission Path of Noise

There are the following four noise transmission paths.

Full Closed Control

Question

Is there a Servo System that has full-closed control?

Answer

Full-closed control is possible by installing a DeviceNet Communications Unit (R88A-NCW152-DRT) in an OMNUC W-series Servo Driver.

A DeviceNet Communications Unit provides a DeviceNet communications interface and position control functions. The Servo Driver can be treated as a slave in the DeviceNet network and used as a Network Driver. Phases A, B, and Z of the external encoder can be incorporated into the DeviceNet Communications Unit to enable full closed-loop control.

Command Pulse Setting for Operating at 3000 r/min for Various Resolutions

Question

Command Pulse Setting for Operating at 3000 r/min for Various Resolutions

Answer

Resolution Setting (Pins 4 and 5)

Note:
If the resolution is 1,000 pulses/rotation, the motor makes 3,000 r/min for a 50-kpps command pulse.
If the resolution is 10,000 pulses/rotation, the motor makes 3,000 r/min for a 500-kpps command pulse.
If the resolution is 500 pulses/rotation, the motor makes 3,000 r/min for a 25-kpps command pulse.
If the resolution is 5,000 pulses/rotation, the motor makes 3,000 r/min for a 250-kpps command pulse.