Balluff BNI EIP-50 105-Z015 Series Instruction Manual

Machine Automation Controller NJ/NX-series
EtherNet/IPTM
Connection Guide
Balluff GmbH
Network Module
(BNI EIP-50[]-105-Z015)
P504-E1-01

About Intellectual Property Rights and Trademarks
Microsoft product screen shots reprinted with permission from Microsoft Corporation.
Windows is a registered trademark of Microsoft Corporation in the USA and other countries.
ODVA and EtherNet/IPTM are trademarks of ODVA.
EtherCAT® is registered trademark and patented technology, licensed by Beckhoff Automation
GmbH, Germany.
Sysmac is a trademark or registered trademark of OMRON Corporation in Japan and other
countries for OMRON factory automation products.
Company names and product names in this guide are the trademarks or registered trademarks
of their respective companies.

Table of Contents
1. Related Manuals.......................................................................................... 1
2. Terms and Definitions ................................................................................ 3
3. Precautions.................................................................................................. 4
4. Overview ...................................................................................................... 5
5. Applicable Devices and Device Configuration........................................ 6
5.1. Applicable Devices.................................................................................. 6
5.2. Device Configuration............................................................................... 7
6. EtherNet/IP Settings.................................................................................... 9
6.1. Parameters.............................................................................................. 9
6.2. Global Variables.................................................................................... 10
6.3. Tag Sets................................................................................................ 15
7. EtherNet/IP Connection Procedure......................................................... 16
7.1. Work Flow ............................................................................................. 16
7.2. Balluff Network Module Setup............................................................... 18
7.3. Controller Setup.................................................................................... 23
7.4. Network Settings................................................................................... 34
7.5. EtherNet/IP Communication Status Check........................................... 51
8. Initialization Method.................................................................................. 59
8.1. Initializing a Controller........................................................................... 59
9. Revision History........................................................................................ 60

1．Related Manuals
1
1. Related Manuals
To ensure system safety, make sure to always read and follow the information provided in all
Safety Precautions and Precautions for Safe Use in the manuals for each device which is
used in the system.
The table below lists the manuals provided by Balluff GmbH (hereinafter referred to as
"Balluff") and OMRON Corporation (hereinafter referred to as "OMRON"), which pertain to this
guide.
Manufacturer Cat. No. Model Manual name
OMRON W500
NJ501-[]5[][]
NJ501-[]4[][]
NJ501-[]3[][]
NJ301-12[][]
NJ301-11[][]
NJ101-10[][]
NJ101-90[][]
NJ-series CPU Unit
Hardware User's Manual
OMRON W535
NX701-17[][]
NX701-16[][]
NX-series
CPU Unit
Hardware User's Manual
OMRON W578
NX1P2-11[][][][]
NX1P2-10[][][][]
NX1P2-90[][][][]
NX-series
NX1P2 CPU Unit
Hardware User's Manual
OMRON W501
NX701-17[][]
NX701-16[][]
NX1P2-11[][][][]
NX1P2-10[][][][]
NX1P2-90[][][][]
NJ501-[]5[][]
NJ501-[]4[][]
NJ501-[]3[][]
NJ301-12[][]
NJ301-11[][]
NJ101-10[][]
NJ101-90[][]
NJ/NX-series
CPU Unit
Software User's Manual
OMRON W506 NJ/NX-series
CPU Unit Built-in EtherNet/IPTM Port
User's Manual
OMRON W504 SYSMAC-SE2[][][] Sysmac Studio Version 1
Operation Manual
OMRON 0969584-7 W4S1-05[]
W4S1-03B Switching Hub W4S1-series
Users Manual
OMRON 9540393-4 E2E(Q)-[]-IL[] PROXIMITY SENSOR
INSTRUCTION SHEET
OMRON 9540292-0 E2E(Q)-[]-IL[] PROXIMITY SENSOR INDEX LIST

1．Related Manuals
2
Manufacturer Cat. No. Model Manual name
Balluff 933690-726 BNI EIP-50[]-105-Z015 BNI EIP-502-105-Z015
BNI EIP-508-105-Z015
EtherNet/IPTM IP67 Modules
User’s Guide
Balluff 893539 BNI EIP-50[]-105-Z015 BNI EIP-508-105-Z015
IP67 Modules
8IO-Link/In-/Outputs, 8 In-/Outputs
User’s Guide

2．Terms and Definitions
3
2. Terms and Definitions
The terms and definitions used in this guide are given below.
Term Explanation and Definition
node A node refers to a relay point, a junction point or an end point on an
EtherNet/IP network made up of devices having an EtherNet/IP port.
A device with one EtherNet/IP port is recognized as one node and two
EtherNet/IP ports as two nodes on an EtherNet/IP network.
tag A tag is a unit that is used to exchange data with tag data links.
Data is exchanged between the local network variables and remote
network variables specified in the tags or between specified I/O memory
areas.
tag set When a connection is established, from 1 to 8 tags (including Controller
status) is configured as a tag set. Each tag set represents the data that is
linked for a tag data link connection. Tag data links are therefore created
through a connection between one tag set and another tag set.
A tag set name must be set for each tag set.
tag data links The standard EtherNet/IP implicit communications are called tag data
links. Tag data links enable cyclic tag data exchanges on an EtherNet/IP
network between Controllers or between Controllers and other devices.
connection A connection is used to exchange data as a unit within which data
concurrency is maintained.
connection type There are two kinds of connection types for tag data links.
One is a multi-cast connection, and the other is a unicast (point-to-point)
connection. The multi-cast connection sends an output tag set in one
packet to more than one node. The unicast connection separately sends
one output tag set to each node. Therefore, the multi-cast connection
can reduce the communications load if one output tag set is sent to more
than one node.
originator and target To perform tag data links, it is necessary to open connections between
nodes that perform tag data links. The node that requests the connection
is called the originator, and the node that receives the request is called
the target.
tag data link
parameters The information that is set to perform tag data links, including tags, tag sets and connections, is called tag data link parameters.
EDS file A file that describes information unique to a device such as the number
of I/O points for an EtherNet/IP device. The connections that define the
tag data links can be set by installing this file in Network Configurator.

3．Precautions
4
3. Precautions
(1) Understand the specifications of devices which are used in the system. Allow some
margin for ratings and performance. Provide safety measures, such as installing a safety
circuit, in order to ensure safety and minimize the risk of abnormal occurrence.
(2) To ensure system safety, make sure to always read and follow the information provided
in all Safety Precautions and Precautions for Safe Use in the manuals for each device
which is used in the system.
(3) The user is encouraged to confirm the standards and regulations that the system must
conform to.
(4) It is prohibited to copy, to reproduce, and to distribute a part or the whole of this guide
without the permission of OMRON Corporation.
(5) The information contained in this guide is current as of February 2018. It is subject to
change for improvement without notice.
The following notations are used in this guide.
Indicates a potentially hazardous situation which, if not avoided,
may result in minor or moderate injury, or may result in serious
injury or death. Additionally there may be significant property
damage.
Indicates a potentially hazardous situation which, if not avoided,
may result in minor or moderate injury or property damage.
Precautions for Correct Use
Precautions on what to do and what not to do to ensure proper operation and performance.
Additional Information
Additional information to read as required.
This information is provided to increase understanding or make operation easier.
Symbol
The filled circle symbol indicates operations that you must do.
The specific operation is shown in the circle and explained in the text.
This example shows a general precaution for something that you must do.

4．Overview
5
4. Overview
This guide describes procedures for connecting a Balluff Network Module (BNI
EIP-50[]-105-Z015) (hereinafter referred to as the "Network Module") to an OMRON
NJ/NX-series Machine Automation Controller (hereinafter referred to as the "Controller") via
EtherNet/IP and for checking their communication status.
Refer to Section 6. EtherNet/IP Settings and Section 7. EtherNet/IP Connection Procedure to
understand setting methods and key points to operate EtherNet/IP tag data links.
The OMRON E2E-series IO-Link Proximity Sensor (hereinafter referred to as the "Proximity
Sensor") is used in this guide in order to check data that is sent and received between the
Controller and the Network Module.

5．Applicable Devices and Device Configuration
6
5. Applicable Devices and Device Configuration
5.1. Applicable Devices
The applicable devices are as follows:
Manufacturer Name Model
OMRON NJ/NX-series CPU Unit
NX701-17[][]
NX701-16[][]
NX1P2-11[][][][]
NX1P2-10[][][][]
NX1P2-90[][][][]
NJ501-[]5[][]
NJ501-[]4[][]
NJ501-[]3[][]
NJ301-12[][]
NJ301-11[][]
NJ101-10[][]
NJ101-90[][]
Balluff Network Module BNI EIP-502-105-Z015
BNI EIP-508-105-Z015
Precautions for Correct Use
In this guide, the devices with models and versions listed in 5.2. Device Configuration are
used as examples of applicable devices to describe the procedures for connecting the
devices and checking their connection.
You cannot use devices with versions lower than the versions listed in 5.2.
To use the above devices with models not listed in 5.2. or versions higher than those listed in
5.2., check the differences in the specifications by referring to the manuals before operating
the devices.
Additional Information
This guide describes the procedures for establishing the network connection.
It does not provide information on operation, installation, wiring method, device functionality,
or device operation, which is not related to the connection procedures.
Refer to the manuals or contact the device manufacturer.

5．Applicable Devices and Device Configuration
7
5.2. Device Configuration
The hardware components to reproduce the connection procedures in this guide are as
follows:
Manufacturer
Name
Model
Version
OMRON
NJ-series CPU Unit
(Built-in EtherNet/IP port)
NJ501-1500
Ver.1.14
OMRON
Power Supply Unit
NJ-PA3001
OMRON
Switching hub
W4S1-05C
Ver.1.0
-
Switching hub power supply
(24 VDC)
-
OMRON
Sysmac Studio
SYSMAC-SE2[][][]
Ver.1.18
OMRON
Network Configurator
(Included in Sysmac Studio)
Ver.3.61
OMRON
IO-Link Proximity Sensor
E2E-X3B4-M1TJ-IL3
Ver.1.00
-
Personal computer
(OS: Windows 7)
-
-
USB cable
(USB 2.0 type B connector)
-
-
LAN cable (STP (shielded,
twisted-pair) cable of Ethernet
category 5 or higher)
-
Balluff
Industrial Ethernet cable
(M12 straight male to RJ45,
double-ended)
BCC M414-E894-8G-672
-ES64N9-006
Balluff
Network Module
BNI EIP-508-105-Z015
H6_S4.2
Balluff
EDS file
BNI EIP-508-105-Z015.eds
1.1(Major
Revision: 4)
Balluff
Icon file
BNI EIP-508-105-Z015.ico
-
Module / sensor power supply
(24 VDC)
-
-
Actuator power supply (24 VDC)
-
Precautions for Correct Use
Prepare the EDS file listed above.
To obtain the EDS file, contact Balluff GmbH.
(M12)
USB cable
LAN cable
NJ501-1500
(Built-in EtherNet/IP port)
W4S1-05C
BNI EIP-508-105-Z015
Personal computer
(Sysmac Studio and
Network Configurator
installed,
OS: Windows 7）
Industrial
Ethernet
cable
Module / sensor power supply
Actuator power supply
E2E-X3B4-M1TJ-IL3
Switching hub power supply

5．Applicable Devices and Device Configuration
8
Precautions for Correct Use
Note that the EDS file specified in this Clause 5.2. is not compatible with versions of the
Network Module earlier than "H5_S[].[]". You need the EDS file with a different version that is
compatible with earlier versions of the Network Module.
Precautions for Correct Use
When there is an icon file specific to the device, the icon file and the EDS file must be stored
in the same folder.
Precautions for Correct Use
Update Sysmac Studio and Network Configurator to the versions specified in this Clause 5.2.
or to higher versions. If you use a version higher than the one specified, the procedures and
related screenshots described in Section 7. and the subsequent sections may not be
applicable. In that case, use the equivalent procedures described in this guide by referring to
the Sysmac Studio Version 1 Operation Manual (Cat. No. W504) and Network Configurator
Online Help.
Additional Information
For specifications of the switching hub power supply, refer to the Switching Hub W4S1-series
Users Manual (Cat. No. 0969584-7).
Additional Information
For specifications of the Module / sensor and Actuator power supplies, refer to the BNI
EIP-508-105-Z015 IP67 Modules 8 IO-Link/In-/Outputs, 8 In-/Outputs User's Guide (893539).
Additional Information
The system configuration in this guide uses USB for the connection between the personal
computer and the Controller. For information on how to install the USB driver, refer to A-1
Driver Installation for Direct USB Cable Connection of the Sysmac Studio Version 1
Operation Manual (Cat. No. W504).
For NX1P2 Controllers, there is no need to install the USB driver because they do not have a
USB port.
Additional Information
The NX1P2 Controller, if used, should be connected to your personal computer with an
Ethernet cable. For information on how to connect the cable, refer to 6-2 Going Online with a
Controller of the Sysmac Studio Version 1 Operation Manual (Cat. No. W504).

6．EtherNet/IP Settings
9
6. EtherNet/IP Settings
This section describes the parameters, global variables and tag sets that are all defined in this
guide.
Hereinafter, the Network Module is referred to as the "Destination Device" in some
descriptions.
6.1. Parameters
The parameters set in this guide are shown below.
6.1.1. EtherNet/IP Communications Settings
The parameters required to connect the Controller and the Network Module via EtherNet/IP
are shown below.
Item Controller (Node 1) Network Module (Node 2)
IP address 192.168.250.1 192.168.250.2
Subnet mask 255.255.255.0 255.255.255.0
6.1.2. Destination Device Settings
The parameter of the Network Module is shown below.
Item Set value Remarks
0015 Port function 1 Port 0: IO-Link mode
Ports 1-7: Standard I/O mode
The following figure shows the data configuration of 0015 Port function and the relationship
between each port and set value of 0015 Port function. The IO-Link mode is set when the set
value for port is 01, whereas the standard I/O mode is set when the set value for port is 00.
With Network Configurator, the set value of 0015 Port function is "1" in decimal that
represents a binary value of "00 00 00 00 00 00 00 01".
0015 Port function
Bit 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
Set value 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1
For example, if setting Ports 0-2 to IO-Link mode and Ports 3-7 to standard I/O mode, the set
value of 0015 Port function will be "21" in decimal that represents a binary value of "00 00 00
00 00 01 01 01".
Port 7
set value
Port 6
set value
Port 5
set value
Port 4
set value
Port 3
set value
Port 2
set value
Port 1
set value
Port 0
set value

6．EtherNet/IP Settings
10
6.2. Global Variables
The Controller treats the data in tag data links as global variables.
The following tables show the global variables and their related settings.
■Output area (Controller to Network Module)
Name Data type Network publish Data size (byte)
EIP002_Standard_IO_ports_OUT BYTE[6] Output 6
EIP002_IOLink_port0_1_OUT BYTE[64] Output 64
EIP002_IOLink_port2_3_OUT BYTE[64] Output 64
EIP002_IOLink_port4_5_OUT
BYTE[64]
Output
64
EIP002_IOLink_port6_7_OUT BYTE[64] Output 64
*Relationship between the global variables and the Network Module data
Global variable
Network Module
Data allocation Bit
7 6 5 4 3 2 1 0
EIP002_Standard_IO_
ports_OUT[0]
Standard
I/O ports
O32 O34 O22 O24 O12 O14 O02 O04
EIP002_Standard_IO_
ports_OUT[1]
O72 O74 O62 O64 O52 O54 O42 O44
EIP002_Standard_IO_
ports_OUT[2]
R32 R34 R22 R24 R12 R14 R02 R04
EIP002_Standard_IO_
ports_OUT[3]
R72 R74 R62 R64 R52 R54 R42 R44
EIP002_Standard_IO_
ports_OUT[4]
0 0 0 0 0 0 0 0
EIP002_Standard_IO_
ports_OUT[5]
0 0 0 0 0 DL GO RO
EIP002_IOLink_port0
_1_OUT[0] to [31]
IO-Link port 0 IO-Link port 0 output process data
EIP002_IOLink_port0
_1_OUT[32] to [63]
IO-Link port 1 IO-Link port 1 output process data
EIP002_IOLink_port2
_3_OUT[0] to [31]
IO-Link port 2 IO-Link port 2 output process data
EIP002_IOLink_port2
_3_OUT[32] to [63]
IO-Link port 3 IO-Link port 3 output process data
EIP002_IOLink_port4
_5_OUT[0] to [31]
IO-Link port 4 IO-Link port 4 output process data
EIP002_IOLink_port4
_5_OUT[32] to [63]
IO-Link port 5 IO-Link port 5 output process data
EIP002_IOLink_port6
_7_OUT[0] to [31]
IO-Link port 6 IO-Link port 6 output process data
EIP002_IOLink_port6
_7_OUT[32] to [63]
IO-Link port 7 IO-Link port 7 output process data

6．EtherNet/IP Settings
11
■Input area (Network Module to Controller)
Name Data type Network publish Data size (byte)
EIP002_Standard_IO_ports_IN BYTE[8] Input 8
EIP002_IOLink_port0_1_IN BYTE[96] Input 96
EIP002_IOLink_port2_3_IN BYTE[96] Input 96
EIP002_IOLink_port4_5_IN BYTE[96] Input 96
EIP002_IOLink_port6_7_IN BYTE[96] Input 96
*Relationship between the global variables and the Network Module data
Global variable
Network Module
Data
allocation
Bit
7 6 5 4 3 2 1 0
EIP002_Standard_IO_ports_IN[0]
Standard
I/O ports
I32 I34 I22 I24 I12 I14 I02 I04
EIP002_Standard_IO_ports_IN[1]
I72 I74 I62 I64 I52 I54 I42 I44
EIP002_Standard_IO_ports_IN[2]
S3 S2 S1 S0
EIP002_Standard_IO_ports_IN[3]
S7 S6 S5 S4
EIP002_Standard_IO_ports_IN[4]
O32 O34 O22 O24 O12 O14 O02 O04
EIP002_Standard_IO_ports_IN[5]
O72 O74 O62 O64 O52 O54 O42 O44
EIP002_Standard_IO_ports_IN[6]
0 0 0 0 0 NA PS PA
EIP002_Standard_IO_ports_IN[7]
0 0 0 0 0 0 0 0
EIP002_IOLink_port0_1_IN[0]
IO-Link
port 0
IO-Link port 0 input process data
Stores the process data "Byte0 (PD0)" of the
Proximity Sensor.
EIP002_IOLink_port0_1_IN[1]
IO-Link port 0 input process data
Stores the process data "Byte1 (PD1)" of the
Proximity Sensor.
EIP002_IOLink_port0_1_IN[2] to [31]
IO-Link port 0 input data
EIP002_IOLink_port0_1_IN[32]
0 0 0 0 0 0 DC IOL
EIP002_IOLink_port0_1_IN[33]
SC 0 0 0 0 PDI DF VF
EIP002_IOLink_port0_1_IN[34] to [35]
Vendor ID
EIP002_IOLink_port0_1_IN[36] to [38]
Device ID
EIP002_IOLink_port0_1_IN[39] to [41]
Event 1
EIP002_IOLink_port0_1_IN[42] to [44]
Event 2
EIP002_IOLink_port0_1_IN[45] to [47]
Event 3
EIP002_IOLink_port0_1_IN[48] to [79]
IO-Link
port 1
IO-Link port 1 input data
EIP002_IOLink_port0_1_IN[80]
0 0 0 0 0 0 DC IOL
EIP002_IOLink_port0_1_IN[81]
SC 0 0 0 0 PDI DF VF
EIP002_IOLink_port0_1_IN[82] to [83]
Vendor ID
EIP002_IOLink_port0_1_IN[84] to [86]
Device ID
EIP002_IOLink_port0_1_IN[87] to [89]
Event 1
EIP002_IOLink_port0_1_IN[90] to [92]
Event 2
EIP002_IOLink_port0_1_IN[93] to [95]
Event 3

6．EtherNet/IP Settings
12
Global variable
Network Module
Data
allocation
Bit
7 6 5 4 3 2 1 0
EIP002_IOLink_port2_3_IN[0] to [47]
IO-Link
port 2 Same as for the data allocation "IO-Link port 0"
EIP002_IOLink_port2_3_IN[48] to [95]
IO-Link
port 3 Same as for the data allocation "IO-Link port 1"
EIP002_IOLink_port4_5_IN[0] to [47]
IO-Link
port 4 Same as for the data allocation "IO-Link port 0"
EIP002_IOLink_port4_5_IN[48] to [95]
IO-Link
port 5 Same as for the data allocation "IO-Link port 1"
EIP002_IOLink_port6_7_IN[0] to [47]
IO-Link
port 6 Same as for the data allocation "IO-Link port 0"
EIP002_IOLink_port6_7_IN[48] to [95]
IO-Link
port 7 Same as for the data allocation "IO-Link port 1"

6．EtherNet/IP Settings
13
■Process Data of Proximity Sensor
(Data to be stored in the global variable EIP002_IOLink_port0_1_IN[0] listed in the table for
the input area)
(Data to be stored in the global variable EIP002_IOLink_port0_1_IN[1] listed in the table for
the input area)

6．EtherNet/IP Settings
14
Additional Information
For details on setting the data in tag data links for the Network Module, refer to 5. Integration
and 6. Process Data of the BNI EIP-508-105-Z015 IP67 Modules 8 IO-Link/In-/Outputs, 8
In-/Outputs User's Guide (893539).
Additional Information
With Sysmac Studio, two methods can be used to specify an array for a data type.
After specifying, (1) is converted to (2), and the data type is always displayed as (2).
(1) BOOL[16] / (2) ARRAY[0..15] OF BOOL
In this guide, the data type is simplified by displaying BOOL[16].
(The example above means a BOOL data type with sixteen array elements.)

6．EtherNet/IP Settings
15
6.3. Tag Sets
The tag sets to perform tag data links are shown below.
The data in the tag sets are assigned in ascending order of the following OUT No. and IN No.
■Output area (Controller to Network Module)
Tag set name (Originator variable) Data size (byte)
EIP002_OUT 262
OUT No. Tag name (Global variable) Data size (byte)
1 EIP002_Standard_IO_ports_OUT 6
2
EIP002_IOLink_port0_1_OUT
64
3 EIP002_IOLink_port2_3_OUT 64
4 EIP002_IOLink_port4_5_OUT 64
5 EIP002_IOLink_port6_7_OUT 64
■Input area (Network Module to Controller)
Tag set name (Originator variable) Data size (byte)
EIP002_IN 392
IN No. Tag name (Global variable) Data size (byte)
1 EIP002_Standard_IO_ports_IN 8
2 EIP002_IOLink_port0_1_IN 96
3 EIP002_IOLink_port2_3_IN 96
4 EIP002_IOLink_port4_5_IN 96
5 EIP002_IOLink_port6_7_IN 96

7．EtherNet/IP Connection Procedure
16
7. EtherNet/IP Connection Procedure
This section describes the procedures for connecting the Network Module and the Controller
via EtherNet/IP. The explanation of the procedure for setting up the Controller given in this
guide is based on the factory default settings.
For the initialization, refer to Section 8. Initialization Method.
7.1. Work Flow
Take the following steps to connect the Network Module and the Controller via EtherNet/IP
and to perform tag data links.
7.2. Balluff Network Module Setup
Set up the Balluff Network Module.
↓
7.2.1. Hardware Settings
Connect the cables and the Proximity Sensor to the
Network Module.
↓
7.2.2. Parameter Settings Set the IP address of the Network Module.
↓
7.3. Controller Setup
Set up the Controller.
↓
7.3.1. IP Address Settings
Start Sysmac Studio and set the IP address of the
Controller.
↓
7.3.2. Setting Global Variables
Set global variables to use for tag data links, and
create and export a CSV file in order to use the
variables as tags with Network Configurator.
↓
7.3.3. Transferring the Project Data
Go online with Sysmac Studio and transfer the
project data to the Controller.
↓
7.4. Network Settings
Set EtherNet/IP tag data links.
↓
7.4.1. Starting Network Configurator
and Installing the EDS File
Start Network Configurator and install the EDS file.
↓
7.4.2. Uploading the Network
Configuration
Go online with Network Configurator and upload the
network configuration.
↓
7.4.3. Tag Registration
Import the created CSV file for use with Network
Configurator, and register tags and tag sets.
↓
7.4.4. Setting Connections
Set connections to associate the tag sets of the
target device with the tag sets of the originator
device.

7．EtherNet/IP Connection Procedure
17
↓
7.4.5. Transferring the Tag Data Link
Parameters
Transfer the tag data link parameters to the
Controller.
↓
7.5. EtherNet/IP Communication
Status Check
Confirm that the EtherNet/IP tag data links perform
normally.
↓
7.5.1. Checking the Connection
Status
Check the EtherNet/IP connection status.
↓
7.5.2. Checking Sent and Received
Data
Check that correct data is sent and received.