Mitsubishi Electric MELSERVO MR-MT2010 User manual

SH(NA)030251ENG-B(1702)MEE Printed in Japan Specifications are subject to change without notice.
This Instruction Manual uses recycled paper.
MODEL
MODEL
CODE
General-Purpose AC Servo
MR-MT2000 SERIES INSTRUCTION MANUAL
HEAD OFFICE : TOKYO BLDG MARUNOUCHI TOKYO 100-8310
MODEL
MR-MT2010
MR-MT2100
MR-MT2200
MR-MT2300
MR-MT2400
INSTRUCTION MANUAL
Sensing module
B
B

A - 1
Safety Instructions
Please read the instructions carefully before using the equipment.
To use the equipment correctly, do not attempt to install, operate, maintain, or inspect the equipment until
you have read through this Instruction Manual, Installation guide, and appended documents carefully. Do not
use the equipment until you have a full knowledge of the equipment, safety information and instructions.
In this Instruction Manual, the safety instruction levels are classified into "WARNING" and "CAUTION".
WARNING Indicates that incorrect handling may cause hazardous conditions,
resulting in death or severe injury.
CAUTION Indicates that incorrect handling may cause hazardous conditions,
resulting in medium or slight injury to personnel or may cause physical
damage.
Note that the CAUTION level may lead to a serious consequence depending on conditions.
Please follow the instructions of both levels because they are important to personnel safety.
What must not be done and what must be done are indicated by the following diagrammatic symbols.
Indicates what must not be done. For example, "No Fire" is indicated by .
Indicates what must be done. For example, grounding is indicated by .
In this Instruction Manual, instructions at a lower level than the above, instructions for other functions, and so
on are classified into "POINT".
After reading this Instruction Manual, keep it accessible to the operator.

A - 2
1. To prevent electric shock, note the following
WARNING
Ground the sensing module securely.
Any person who is involved in wiring and inspection should be fully competent to do the work.
Do not attempt to wire the sensing module until it has been installed. Otherwise, it may cause an electric
shock.
Do not operate switches with wet hands. Otherwise, it may cause an electric shock.
The cables should not be damaged, stressed, loaded, or pinched. Otherwise, it may cause an electric
shock.
To avoid an electric shock, insulate the connections of the power supply terminals.
2. To prevent fire, note the following
CAUTION
Install the sensing module on incombustible material. Installing them directly or close to combustibles will
lead to smoke or a fire.
Always connect a circuit protector between the power supply and the power supply (24 V(+)) of the
sensing module, in order to configure a circuit that shuts down the power supply on the side of the
sensing module power supply. If a circuit protector is not connected, a continuous flow of a large current
may cause smoke or a fire when the sensing module malfunctions.
Provide an adequate protection to prevent screws and other conductive matter, oil and other combustible
matter from entering the sensing module.
3. To prevent injury, note the following
CAUTION
Only the voltage specified in the Instruction Manual should be applied to each terminal. Otherwise, a
burst, damage, etc. may occur.
Connect cables to the correct terminals. Otherwise, a burst, damage, etc. may occur.
Ensure that polarity (+/-) is correct. Otherwise, a burst, damage, etc. may occur.
4. Additional instructions
The following instructions should also be fully noted. Incorrect handling may cause a malfunction, injury,
electric shock, fire, etc.
(1) Transportation and installation
CAUTION
Transport the products correctly according to their mass.
Stacking in excess of the specified number of product packages is not allowed.
Install the sensing module in a load-bearing place in accordance with the Instruction Manual.
Do not get on or put heavy load on the equipment.
The equipment must be installed in the specified direction.

A - 3
CAUTION
Leave specified clearances between the sensing module and cabinet walls or other equipment.
Do not install or operate the sensing module which has been damaged or has any parts missing.
Do not block intake and exhaust areas of the sensing module. Otherwise, it may cause a malfunction.
Do not drop or strike the sensing module. Isolate it from all impact loads.
When you keep or use the equipment, please fulfill the following environment.
Item Environment
Ambient
temperature
Operation 0 °C to 60 °C (non-freezing)
Storage -20 ˚C to 65 ˚C (non-freezing)
Ambient
humidity
Operation 5 %RH to 90 %RH (non-condensing)
Storage
Ambience Indoors (no direct sunlight); no corrosive gas, inflammable gas, oil mist or dust
Altitude
2000 m or less above sea level
(When using the MR-MT2000 series at an altitude exceeding 1000 m and up to 2000 m above sea
level, the ambient temperature must be 0 °C to 55 °C.)
Vibration resistance 5.9 m/s2, at 10 Hz to 55 Hz (directions of X, Y and Z axes)
When the product has been stored for an extended period of time, contact your local sales office.
When handling the sensing module, be careful with the sharp edges of the sensing module.
The sensing module must be installed in a metal cabinet.
When fumigants that contain halogen materials, such as fluorine, chlorine, bromine, and iodine, are used
for disinfecting and protecting wooden packaging from insects, they cause malfunction when entering our
products. Please take necessary precautions to ensure that remaining materials from fumigant do not
enter our products, or treat packaging with methods other than fumigation, such as heat treatment.
Additionally, disinfect and protect wood from insects before packing the products.
(2) Wiring
CAUTION
Wire the sensing module correctly and securely. Otherwise, the equipment may operate unexpectedly.
The connection diagrams in this Instruction Manual are shown for sink interfaces, unless stated
otherwise.
The surge absorbing diode installed to the DC relay for control output signals of the sensing module
should be fitted in the specified direction. Otherwise, the emergency stop and other protective circuits
may not operate.
DOCOM
Control output
signal
24 V DC
Sensing module
RA
For sink output interface
DOCOM
Control output
signal
24 V DC
Sensing module
RA
For source output interface

A - 4
(3) Test run and adjustment
CAUTION
Before operation, check and adjust the parameter settings. Improper settings may cause some machines
to operate unexpectedly.
(4) Usage
CAUTION
Immediately turn off the power if smoke, unusual noise, or strange odor is emitted from the sensing
module.
Do not disassemble, repair, or modify the equipment.
Burning or breaking a sensing module may cause a toxic gas. Do not burn or break it.
Connect the sensing module to the specified controller.
(5) Corrective actions
CAUTION
Ensure safety by confirming the power off, etc. before performing corrective actions. Otherwise, it may
cause an accident.
When an alarm occurs, eliminate its cause, ensure safety, and deactivate the alarm to restart operation.
Provide an adequate protection to prevent unexpected restart after an instantaneous power failure.
(6) Maintenance, inspection and parts replacement
CAUTION
Do not touch the connector contacts.
It is recommended that the sensing module be replaced every 10 years when it is used in general
environment.
When using the sensing module that has not been energized for an extended period of time, contact your
local sales office.
(7) General instruction
To illustrate details, the equipment in the diagrams of this Instruction Manual may have been drawn
without covers and safety guards. When the equipment is operated, the covers and safety guards must
be installed as specified. Operation must be performed in accordance with this Instruction Manual.

A - 5
DISPOSAL OF WASTE
Please dispose a sensing module and other options according to your local laws and regulations.
EEP-ROM life
The number of write times to the EEP-ROM, which stores parameter settings, etc., is limited to 100,000. If
the total number of the following operations exceeds 100,000, the sensing module may malfunction when the
EEP-ROM reaches the end of its useful life.
Write to the EEP-ROM due to parameter setting changes
Compliance with global standards
Refer to app. 1 for the compliance with global standards.
«About the manual»
You must have this Instruction Manual and the following manual to use this sensing module. Ensure to
prepare them to use the sensing module safely.
Relevant manuals
Manual name Manual No.
MELSEC iQ-R Motion Controller Programming Manual (Common) IB-0300237
«Cables used for wiring»
Wires mentioned in this Instruction Manual are selected based on an ambient temperature of 40 ˚C.
«U.S. customary units»
U.S. customary units are not shown in this manual. Convert the values if necessary according to the
following table.
Quantity SI (metric) unit U.S. customary unit
Mass 1 [kg] 2.2046 [lb]
Length 1 [mm] 0.03937 [inch]
Torque 1 [N•m] 141.6 [oz•inch]
Moment of inertia 1 [(× 10-4 kg•m2)] 5.4675 [oz•inch2]
Load (thrust load/axial load) 1 [N] 0.2248 [lbf]
Temperature N [°C] × 9/5 + 32 N [°F]

A - 6
MEMO

1
CONTENTS
1. INTRODUCTION 1- 1 to 1- 4
1.1 Summary........................................................................................................................................... 1- 1
1.2 Model designation............................................................................................................................. 1- 2
1.3 Common specifications..................................................................................................................... 1- 2
1.4 Configuration example including peripheral equipment ................................................................... 1- 3
2. SYSTEM CONFIGURATION 2- 1 to 2- 6
2.1 System configuration ........................................................................................................................ 2- 1
2.2 Station mode/axis mode ................................................................................................................... 2- 2
2.3 Extension module connectable to the head module......................................................................... 2- 2
2.4 Maximum number of connections on a network ............................................................................... 2- 3
2.4.1 Station mode .............................................................................................................................. 2- 3
2.4.2 Axis mode (settable only when MR-MT2200 is connected) ...................................................... 2- 5
2.5 Compatible servo system controller ................................................................................................. 2- 6
2.6 Engineering software ........................................................................................................................ 2- 6
3. INSTALLATION 3- 1 to 3- 14
3.1 Connection and removal of modules ................................................................................................ 3- 1
3.2 How to mount a module.................................................................................................................... 3- 4
3.2.1 Mounting a module on a DIN rail ............................................................................................... 3- 4
3.2.2 Mounting a module with screws................................................................................................. 3- 6
3.3 Installation direction and clearances ................................................................................................ 3- 7
3.4 SSCNET III cable connection ........................................................................................................... 3- 8
3.5 How to wire connectors ................................................................................................................... 3-10
3.6 Noise reduction techniques ............................................................................................................. 3-12
4. MR-MT2010 SSCNET III/H HEAD MODULE 4- 1 to 4-10
4.1 Summary........................................................................................................................................... 4- 1
4.2 Standard specifications..................................................................................................................... 4- 1
4.3 Function list....................................................................................................................................... 4- 1
4.4 Parts identification............................................................................................................................. 4- 2
4.5 Station number selection rotary switch............................................................................................. 4- 3
4.6 Status display LEDs.......................................................................................................................... 4- 4
4.7 Signals and wiring............................................................................................................................. 4- 5
4.7.1 Pin assignment........................................................................................................................... 4- 5
4.7.2 Signal (device) explanations ...................................................................................................... 4- 6
4.7.3 Connections of the power circuit................................................................................................ 4- 7
4.7.4 Detailed explanation of interfaces.............................................................................................. 4- 8
5. MR-MT2100 I/O MODULE 5- 1 to 5- 8
5.1 Summary........................................................................................................................................... 5- 1
5.2 Specification list ................................................................................................................................ 5- 1
5.3 Function list....................................................................................................................................... 5- 2
5.4 Parts identification............................................................................................................................. 5- 2

2
5.5 Status display LEDs.......................................................................................................................... 5- 3
5.6 Signals and wiring............................................................................................................................. 5- 3
5.6.1 Pin assignment........................................................................................................................... 5- 3
5.6.2 Signal (device) explanations ...................................................................................................... 5- 4
5.6.3 Connecting the interface power supply for output signal ........................................................... 5- 5
5.6.4 Detailed explanation of interfaces.............................................................................................. 5- 6
6. MR-MT2200 PULSE I/O MODULE 6- 1 to 6-22
6.1 Summary........................................................................................................................................... 6- 1
6.2 Standard specifications..................................................................................................................... 6- 1
6.3 Function list....................................................................................................................................... 6- 2
6.4 Parts identification............................................................................................................................. 6- 2
6.5 Switching the mode between the station mode and axis mode ....................................................... 6- 3
6.5.1 Mode select switch (SW1).......................................................................................................... 6- 3
6.5.2 Settings in the station mode....................................................................................................... 6- 4
6.6 Status display LEDs.......................................................................................................................... 6- 5
6.7 Signals and wiring............................................................................................................................. 6- 6
6.7.1 Pin assignment........................................................................................................................... 6- 6
6.7.2 Signal (device) explanations ...................................................................................................... 6- 8
6.7.3 Detailed explanation of interfaces............................................................................................. 6-12
6.7.4 Command pulse output form..................................................................................................... 6-21
6.7.5 Input pulse form ........................................................................................................................ 6-22
7. MR-MT2300 ANALOG I/O MODULE 7- 1 to 7- 8
7.1 Summary........................................................................................................................................... 7- 1
7.2 Standard specifications..................................................................................................................... 7- 1
7.3 Function list....................................................................................................................................... 7- 1
7.4 Parts identification............................................................................................................................. 7- 2
7.5 Status display LEDs.......................................................................................................................... 7- 3
7.6 Signals and wiring............................................................................................................................. 7- 4
7.6.1 Pin assignment........................................................................................................................... 7- 4
7.6.2 Signal (device) explanations ...................................................................................................... 7- 5
7.6.3 Description of interfaces............................................................................................................. 7- 6
8. MR-MT2400 ENCODER I/F MODULE 8- 1 to 8- 4
8.1 Summary........................................................................................................................................... 8- 1
8.2 Standard specifications..................................................................................................................... 8- 1
8.3 Function list....................................................................................................................................... 8- 1
8.4 Parts identification............................................................................................................................. 8- 2
8.5 Status display LEDs.......................................................................................................................... 8- 2
8.6 Signals and wiring............................................................................................................................. 8- 3
8.6.1 Pin assignment........................................................................................................................... 8- 3
8.6.2 Connecting SSI-compatible encoders........................................................................................ 8- 4
9. PARAMETERS 9- 1 to 9-106
9.1 Station mode..................................................................................................................................... 9- 1
9.1.1 Parameter list ............................................................................................................................. 9- 1

3
9.1.2 Detailed list of parameters ........................................................................................................ 9-19
9.2 Axis mode ........................................................................................................................................ 9-91
9.2.1 Parameter list ............................................................................................................................ 9-91
9.2.2 Detailed list of parameters ........................................................................................................ 9-96
10. TROUBLESHOOTING 10- 1 to 10-32
10.1 Explanations of the lists ................................................................................................................ 10- 1
10.2 Alarm list ....................................................................................................................................... 10- 2
10.3 Warning list ................................................................................................................................... 10- 5
10.4 Remedies for alarms..................................................................................................................... 10- 6
10.5 Remedies for warnings ................................................................................................................ 10-28
10.6 Trouble which does not trigger an alarm/warning ....................................................................... 10-29
10.6.1 MR-MT2010 SSCNET III/H head module............................................................................. 10-29
10.6.2 MR-MT2100 I/O module........................................................................................................ 10-29
10.6.3 MR-MT2200 pulse I/O module.............................................................................................. 10-30
10.6.4 MR-MT2300 analog I/O module............................................................................................ 10-30
10.6.5 MR-MT2400 encoder I/F module .......................................................................................... 10-31
11. DIMENSIONS 11- 1 to 11- 4
APPENDIX App. - 1 to App. - 12
App. 1 Compliance with global standards .......................................................................................App. - 1

4
MEMO

1. INTRODUCTION
1 - 1
1. INTRODUCTION
1.1 Summary
The sensing module MR-MT2000 series have four types of extension modules, the I/O module, pulse I/O
module, analog I/O module, and encoder I/F module. Up to four extension modules can be connected to one
SSCNET III/H head module. These modules are used to receive and output signals synchronized with
SSCNET III/H communications.
These modules realize a high-accuracy, wire-saving system with their distributed installations.
MR-MT2010
SSCNET III/H head module
MR-MT2100
I/O module
MR-MT2200
pulse I/O module
MR-MT2300
analog I/O module
MR-MT2400
encoder I/F module
Model Name Description
MR-MT2010 SSCNET III/H head module The SSCNET III/H head module is used for SSCNET III/H
communications. This module is necessary to use a sensing module.
Connect extension modules to this module. This module can be used
alone because it has digital I/Os.
MR-MT2100 I/O module Digital signals are inputted to and outputted from the I/O module. This
module processes I/O signals synchronized with SSCNET III/H
communications. MR-MT2010 is necessary to use this module.
MR-MT2200 Pulse I/O module General-purpose pulse trains are inputted to and outputted from the
pulse I/O module. This module outputs position commands in pulses
through SSCNET III/H communications and performs position control by
using general-purpose pulse train drivers and servo amplifiers. In
addition, feedback pulses can also be inputted.
This module processes general-purpose pulse train signals synchronized
with SSCNET III/H communications. MR-MT2010 is necessary to use
this module.
MR-MT2300 Analog I/O module Analog signals are inputted to and outputted from the analog I/O module.
This module processes I/O signals synchronized with SSCNET III/H
communications. MR-MT2010 is necessary to use this module.
MR-MT2400 Encoder I/F module The encoder I/F module supports open-standard encoder interfaces. This
module processes signals synchronized with SSCNET III/H
communications. MR-MT2010 is necessary to use this module.

1. INTRODUCTION
1 - 2
1.2 Model designation
(1) Rating plate
The following shows an example of the rating plate for explanation of each item.
Serial number
Model
IP rating, Manual number
Applicable power supply
Rated output power
Standard number
Ambient temperature
KC certification number
The year and month of manufacture
Country of origin
MR-MT2010
IP20 MAN.: IB(NA)0300331
DATE: 2016-07
TOKYO 100-8310, JAPAN MADE IN JAPAN
AC SERVO
SER. A67001001
INPUT : 1.0A DC24V
OUTPUT : 0.8A DC24V
STD.: IEC/EN 61800-5-1
Max. Surrounding Air Temp.: 60°C
MSIP-REI-MEK-TC301A160G51
(2) Model
The following describes what each block of a model name indicates.
Series
Symbol Module name
2010 SSCNET III/H head module
2100 I/O module
2200 Pulse I/O module
2300 Analog I/O module
2400 Encoder I/F module
Module name
MR - MT 2 0 1 0
1.3 Common specifications
The following table lists the common specifications of the MR-MT2000 series.
Item Specification
Compliance
to global
standards
CE marking EMC:EN 61800-3
UL standard UL 508C
Structure (IP rating) Natural cooling, open (IP20)
Ambient
temperature
Operation 0 °C to 60 °C (non-freezing) (Note)
Storage -20 ˚C to 65 ˚C (non-freezing)
Environment
Ambient
humidity
Operation 5 %RH to 90 %RH (non-condensing)
Storage
Ambience Indoors (no direct sunlight),
free from corrosive gas, flammable gas, oil mist, dust, and dirt
Altitude 2000 m or less above sea level (Note)
Vibration resistance
5.9 m/s2, at 10 Hz to 55 Hz (directions of X, Y and Z axes)
Note. When using the MR-MT2000 series at an altitude exceeding 1000 m and up to 2000 m above sea level, the ambient temperature
must be 0 °C to 55 °C.

1. INTRODUCTION
1 - 3
1.4 Configuration example including peripheral equipment
POINT
This section describes a combination example of extension modules.
Combinations other than the example are also available. For details, refer to
chapter 2.
Devices other than the sensing module are optional or recommended products.
The following figure shows a configuration including peripheral equipment as an example of when each MR-
MT2010, MR-MT2100, MR-MT2200, MR-MT2300, and MR-MT2400 is used.
24 V(+)
24G
FG
Personal
computer
Engineering
software
Circuit
protector
Digital I/O
Head module CN1A,
servo amplifier CN1A,
or cap
Servo system controller,
head module CN1B,
or servo amplifier CN1B
MR-
MT2010
MR-
MT2100
MR-
MT2200
MR-
MT2300
MR-
MT2400
General-purpose
pulse train signal
Analog I/O Open-standard
encoder
Interface input
CN1A
CN1B
-+
24 V DC
power
supply
24 V(+)
24G
FG
-+
24 V DC
power
supply
Servo amplifier
Switch
Servo amplifier
Controlle
r
SSCNET III/H

1. INTRODUCTION
1 - 4
MEMO

2. SYSTEM CONFIGURATION
2 - 1
2. SYSTEM CONFIGURATION
2.1 System configuration
POINT
Attach a connector cover, which is supplied with a head module, to the rightmost
extension module. Attach a connector cover to a head module when the head
module is used alone.
For the module configuration of the sensing module, the head module must be connected at the leftmost
side, and up to four extension modules can be connected at the right side of the head module. The head
module can be used alone.
MR-MT2010 MR-MT2100 MR-MT2200 MR-MT2300 MR-MT2400
Head module Extension modules Connector cove
r
(Supplied with
a head module)
A module group consisting of one head module and extension modules connected at the right side of the
head module is called one block. The following figure shows examples of blocks.
Servo system controller
1 block 1 block
Servo system controller
1 block

2. SYSTEM CONFIGURATION
2 - 2
2.2 Station mode/axis mode
POINT
Only when the MR-MT2200 pulse I/O module is connected to the head module,
the station mode or axis mode can be selected. All other modules operate in the
station mode, and the axis mode cannot be set.
When the MR-MT2200 series is used, two modes are available.
Mode Description
Station mode Select this mode to use the pulse I/O function for a purpose other than for driving motors.
Servo amplifier axes are not occupied.
Axis mode
Select this mode to drive motors.
Use this mode for driving stepping motors through general-purpose pulse train drivers just like
servo amplifier axes by outputting position commands in general-purpose pulse train signals
from a servo system controller.
Axes are occupied by the number of motor axes connected to MR-MT2200. Axes are
occupied in the same way as when MR-J4-B servo amplifiers are used.
2.3 Extension module connectable to the head module
CAUTION
Do not connect the extension modules exceeding the maximum number of
connectable modules to the head module. Otherwise, the modules may
malfunction.
(1) Connectable extension modules
The following table lists the extension modules connectable to the MR-MT2010 SSCNET III/H head
module.
Model Name
MR-MT2100 I/O module
MR-MT2200 Pulse I/O module
MR-MT2300 Analog I/O module
MR-MT2400 Encoder I/F module
(2) The connectable number of extension modules
The following describes the connectable number of extension modules.
Up to four extension modules can be connected to one head module.
No restrictions are applied to the connection order of extension modules.
When MR-MT2400 is used, up to two MR-MT2400 modules can be connected to one head module.
Do not connect the extension modules in the axis mode and station mode together to one head
module.
(When MR-MT2200 is used in the axis mode, other extension modules or MR-MT2200 modules in the
station mode cannot be connected to one head module.)
When the station mode is selected, refer to section 2.4.1 for the number of connectable stations.
When the axis mode is selected, refer to section 2.4.2 for the number of connectable axes.

2. SYSTEM CONFIGURATION
2 - 3
2.4 Maximum number of connections on a network
POINT
When MR-MT2200 is used in the axis mode, no restrictions are applied to the
number of connectable stations because one MR-MT2200 module is handled as
an axis just like servo amplifiers.
2.4.1 Station mode
The following table lists the number of connectable stations of the sensing module in one SSCNET III/H
system.
SSCNET III/H communication cycle [ms] Number of connectable
stations
0.888 or more Max. 4
0.444 Max. 2
0.222 Max. 1
Servo system controlle
r
Servo amplifiers
Station 1
Station 2
Station 3
Station 4
Max. four stations
(The number of stations depends on the
SSCNET III/H communication cycle.)
For the sensing module, each extension module occupies one station.
When the head module and an extension module are used together, one station is occupied by the
combination of the head module and the extension module next to it. However, when the head module is
used alone, the head module itself occupies one station. The following shows how stations are counted.

2. SYSTEM CONFIGURATION
2 - 4
Examples of how stations are counted
One head
module
One head module
+ One extension
module
One head module
+ Four extension modules
Two head modules
+ Two extension modules each for one
head module (four extension modules in
total)
Configuration
diagram
Station 1 Station 1
Station 1
Station 2
Station 3
Station 4
Station 1 Station 3
Station 2 Station 4
Number of
occupied
stations
1 station 1 station 4 stations 4 stations
One system allows up to four blocks to be connected.
Servo system controller
1 block
Max. four blocks
1 block 1 block1 block

2. SYSTEM CONFIGURATION
2 - 5
2.4.2 Axis mode (settable only when MR-MT2200 is connected)
POINT
When MR-MT2200 is used in the axis mode, up to four axes can be connected
to one head module.
Up to two axes can be connected to one MR-MT2200 module. However, when
the feedback pulse input is used, only one axis can be connected to one MR-
MT2200 module.
The number of connectable axes in one system depends on the maximum
number of axes of the controller. No restrictions are applied to the number of
connectable head modules in one system.
The maximum number of connectable axes in one SSCNET III/H system is equal to the maximum number of
connectable axes of the servo system controller. The number of axes per one system is the total number of
axes of general-purpose pulse train drivers connected to MR-MT2200 modules and servo amplifiers.
Servo system controlle
r
Servo amplifiers Axis 3 Axis 4 Axis 5 Axis 6(Note)
Axis 1 Axis 2
General-purpose pulse
train drivers
+
Motors
Note. Set the start axis number with the station number selection rotary switches (SW1/SW2) of the head module.