Omega iServer MicroServer EIS-2B User manual

User’s Guide
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EIS-2B and EIS-W
Serial to Ethernet and Internet

It is the policy of OMEGA to comply with all worldwide safety and EMC/EMI regulations that apply.
OMEGA is constantly pursuing certification of its products to the European New Approach Directives. OMEGA will add the CE mark
to every appropriate device upon certification.
The information contained in this document is believed to be correct, but OMEGA Engineering, Inc. accepts no liability for any
errors it contains, and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, patient-connected applications.
This device is marked with the international caution symbol. It is important to read the Setup Guide before installing or
commissioning this device as the guide contains important information relating to safety and EMC.

TABLE OF CONTENT
Part 1: Introduction ....................................................................................................2
1.1 Safety and EMC Considerations ...........................................................2
1.2 Before You Begin ...................................................................................2
1.3 Description..............................................................................................3
Part 2: Hardware ....................................................................................................4
2.1 Mounting ................................................................................................4
2.1.1 Mounting the Wall Mount iServer ............................................4
2.1.2 Mounting the DIN Rail iServer .................................................5
2.1.2.1 Removal from a DIN Rail...........................................................5
2.2 DIP Switches...........................................................................................6
2.2.1 DIP Switch Usage ......................................................................6
2.3 Parts of the iServer Unit .......................................................................7
2.4 Serial Communication Interfaces ........................................................8
2.4.1 Wiring RS232 Interface - Wall Mount iServer .........................9
2.4.2 Wiring RS232 Interface - DIN Rail iServer ..............................9
2.4.3 Wiring RS485 Interface - Wall Mount iServer .......................10
2.4.4 Wiring RS485 Interface - DIN Rail iServer ............................11
2.5 Network Communication Interfaces ..................................................12
2.5.1 10Base-T RJ-45 Pinout ...........................................................12
2.5.2 10Base-T Crossover Wiring ...................................................12
Part 3: Network Configuration ......................................................................................13
3.1 Network Protocols ...............................................................................13
3.2 Ethernet (MAC) Address .....................................................................13
3.3 DHCP .................................................................................................14
3.4 DNS .................................................................................................14
3.5 IP Address ............................................................................................14
3.5.1 Default IP Address ..................................................................15
3.6 Port Number..........................................................................................15
Part 4: Operations ..................................................................................................16
4.1 iConnect Software ...............................................................................17
4.2 Setting a New IP Address over the Network .....................................19
4.3 Setup and Operation using a Web Browser .....................................20
4.3.1 Device Setup............................................................................21
4.3.2 Read Devices ...........................................................................22
4.3.3 Device Query ...........................................................................22
4.3.4 Configuration...........................................................................23
4.3.5 Configure Access Control .....................................................26
4.4 Setting a New IP Address using the Serial Port ...............................28
4.5 Terminal Server unction ......................................................30
4.6 Terminal Emulation .............................................................................31
4.7 Telnet Setup .........................................................................................32
4.8 HTTPget Program.................................................................................34
4.8.1 HTTPget Program using Port 1000 ...........................................34
4.8.2 HTTPget and ARP to Setup Device IP Address ......................36
4.9 ARP Protocol ........................................................................................37
i

4.10 Remote Access (Tunneling) ................................................................38
4.10.1 Remote iServer........................................................................39
4.10.2 Local iServer ...........................................................................40
4.10.3 Tunneling Troubleshooting ...................................................41
4.11 iPORT, COM Port Redirector...............................................................41
4.11.1 iPORT Overview ......................................................................41
4.11.2 iPORT Configurations.............................................................42
4.12 Mail Notifier Software...........................................................................45
4.12.1 Mail Notifier Installation..........................................................45
4.12.2 Program Options Setup and Configuration .........................46
4.12.3 Device Setting Setup and Configuration...............................47
4.13 iLog Software........................................................................................48
Part 5: Specifications.................................................................................................... 49
Part 6: actory Preset Values ......................................................................................51
Appendix A Glossary................................................................................................52
Appendix B IP Address ............................................................................................53
Appendix C IP Netmask............................................................................................54
Appendix D ASCII Chart ..........................................................................................56
ASCII Chart Control Codes .................................................................56
Appendix E iLog Error Messages ...........................................................................57
Part 7: Approvals Information
7.1 Electromagnetic Compatibility (EMC) ...............................................58
7.2 CC ..................................................................................................58
LI T OF TABLE :
Table 2.1 Parts of iServer Unit ...........................................................................................7
Table 2.2 Communication Interfaces - RS232 and RS485 ..............................................8
Table 2.3 Signals and Directions of DB9 Connector - Wall Mount iServer ...................9
Table 2.4 Signals and Directions of Connector - DIN Rail iServer ................................9
Table 2.5 RS485 Half-Duplex Hookup - Wall Mount iServer..........................................10
Table 2.6 RS485 Half-Duplex Hookup - DIN Rail iServer ...............................................11
ii

LI T OF FIGURE :
igure 1.1 Accessing Devices Over the Ethernet ..............................................................3
igure 2.1 Mounting - Wall Mount iServer .........................................................................4
igure 2.2 Mounting - DIN Rail iServer ...............................................................................5
igure 2.3 Removal - DIN Rail iServer ................................................................................5
igure 2.4a DIP Switches - Wall Mount iServer ....................................................................6
igure 2.4b DIP Switches - DIN Rail iServer .........................................................................6
igure 2.5 Parts of the iServer Unit .....................................................................................7
igure 2.6 Multi-point, Half-Duplex RS485 Wiring - Wall Mount iServer .......................10
igure 2.7 Multi-point, Half-Duplex RS485 Wiring - DIN Rail iServer ...........................11
igure 2.8 RJ45 Pinout ......................................................................................................12
igure 2.9 10Base-T Crossover Cable Wiring ................................................................12
igure 3.1 Labeling ............................................................................................................13
igure 3.2 DIP Switch on Bottom Side of iServer ............................................................14
igure 3.3 Telnet Login into the iServer............................................................................15
igure 4.1 Pinging the iServer from MS-DOS Prompt ....................................................16
igure 4.2 Assigning an IP Address using iConnect.......................................................17
igure 4.3 Accessing the iServer’s Home Page Menu.....................................................18
igure 4.4 Access Control .................................................................................................19
igure 4.5 iServer Home Page Menu ................................................................................20
igure 4.6 Login and Adminstrator Password ................................................................20
igure 4.7 Device Setup .....................................................................................................21
igure 4.8 Device Parameters ............................................................................................21
igure 4.9 Error Message ...................................................................................................22
igure 4.10 Read Devices.....................................................................................................22
igure 4.11 Device Query .....................................................................................................22
igure 4.12 Configuration ....................................................................................................23
igure 4.13 Access Control .................................................................................................26
igure 4.14 DIP Switch #1.....................................................................................................28
igure 4.15 Setting the IP address via the Serial Port .......................................................28
igure 4.16 Pinging 192.168.1.70 from the MS-DOS Prompt ............................................29
igure 4.17 Terminal Server Configuration .......................................................................30
igure 4.18 Terminal Emulation ..........................................................................................31
igure 4.19 Tera Term Telnet Connection Screen ............................................................32
igure 4.20 Telnet Setup - iServer Configuration Page ....................................................32
igure 4.21 Telnet Setup - iServer Help Page ....................................................................33
igure 4.22 ARP Commands and Responses ...................................................................37
igure 4.23 Serial Tunneling ................................................................................................38
igure 4.24 Device-to-Device Communication ...................................................................38
igure 4.25 Configuration Page - Remote iServer .............................................................39
igure 4.26 Configuration Page - Local iServer .................................................................40
igure 4.27 Direct Serial Connection ..................................................................................42
igure 4.28 Redirect Serial Connection ..............................................................................42
igure 4.29 iPORT Main Window .........................................................................................43
igure 4.30 COM Port Window.............................................................................................43
igure 4.31 iServer Mail Notifier Main Window ..................................................................45
igure 4.32 iServer Mail Notifier Profile Setup ...................................................................46
igure 4.33 iServer Mail Notifier Device Setting ................................................................47
igure 4.34 iLog Software Logging Data ............................................................................48
igure 5.1 Wall Mount iServer Dimensions ......................................................................50
igure 5.2 DIN Rail iServer Dimensions ...........................................................................50
iii

iv

NOTE , WARNING and CAUTION
Information that is especially important to note is identified by following labels:
• NOTE
• WARNING or CAUTION
• IMPORTANT
• TIP
NOTE: Provides you with information that is important to successfully
setup and use the iServer.
CAUTION or WARNING: Tells you about the risk of electrical shock.
CAUTION, WARNING or IMPORTANT: Tells you of circumstances
or practices that can effect the instrument’s functionality and must
refer to accompanying documents.
TIP: Provides you helpful hints.
1

PART 1
INTRODUCTION
1.1 Safety and EMC Considerations
Refer to the CE Approval Section
EMC Considerations
•Whenever EMC is an issue, always use shielded cables.
•Never run signal and power wires in the same conduit.
•Use twisted-pair wires for signal connections.
•Install Ferrite Bead(s) on signal wires close to the instrument if EMC problems persist.
ailure to follow all instructions and warnings may result in injury!
1.2 Before You Begin
Inspecting Your Shipment: Remove the packing slip and verify that you have received
everything listed. Inspect the container and equipment for signs of damage as soon as
you receive the shipment. Note any evidence of rough handling in transit. Immediately
report any damage to the shipping agent. The carrier will not honor damage claims
unless all shipping material is saved for inspection. After examining and removing the
contents, save the packing material and carton in the event reshipment is necessary.
Customer Service: If you need assistance, please contact the Customer Service
Department nearest you.
Manuals, Software: The latest Operation Manual as well as free configuration software
(iConnect), datalogging software (iLog), and Mail Notifier are available at the website
listed on the cover page of this manual or on the CD-ROM enclosed with your
shipment.
2

1.3 Description
This device can be purchased as a stand alone DIN Rail mounted unit, or
as a bench/wall mount unit.
The iServer is a stand alone Ethernet Server designed to connect devices with serial
interfaces to the Ethernet network using the TCP/IP protocol. It contains Ethernet and
RS232/RS485 interfaces.
The standard features include:
• Use standard Web Browser, TCP connection, HTTPget DOS program or Telnet
Simulation, for network connectivity.
• Install via RS232/RS485 serial port connection.
• Transfer data from RS232/RS485 serial interface to TCP/IP using built-in socket server.
• Use a standard home page or customize Web page for OEM applications.
The following example illustrates how you can hookup the devices with serial interface
on the network using the iServer:
igure 1.1 Accessing Devices Over the Ethernet
COMMUNICATIONS
ETHERNET
DC POWER IN
RESET
+ - N/C
COMPUTER
(COM Port
Redirector)
COMPUTER
(Telnet or
IP-enabled
Programs)
COMPUTER
(Standard
Web Browser)
3

4
PART 2
HARDWARE
2.1 Mounting
2.1.1 Mounting the Wall Mount iServer
Position unit where required. Mark and drill the two #6 screw holes.
After bracket is mounted on the wall, align back of unit over the three bracket clips,
once engaged, slide downward, the unit will snap in place.
igure 2.1 Mounting - Wall Mount iServer
It is recommended that you ground your unit. With one end of a wire
connected to earth ground, the other side can be wraped around the ground
screw, located on the bottom of the case.
If unit is to be mounted on a flat surface, you may take the bottom rubber
feet off the unit.
For overall dimensions of unit, refer to igure 5.1 in Specifications Section.
2.60 [66.0]
1.30 [33.0]
3.67 [93.1]
1.50 [38.1]
1.07 [27.3]
Bracket Clips (3)
Drill 0.14 [3.6] (2 plcs)
Use #6 Screws (Provided)
to Mount the Bracket
Ethernet
Ground Screw
on Rear of Case

5
2.1.2 Mounting the DIN Rail iServer
To install unit onto DIN Rail:
a) Tilt unit, position mounting slot onto DIN Rail, as shown.
b) Push unit towards DIN Rail and it will snap into place.
igure 2.2 Mounting - DIN Rail iServer
2.1.2.1 Removal from a DIN Rail
a) Insert flat screw-driver into tab and push downwards.
b) Unit will detach from DIN Rail.
igure 2.3 Removal - DIN Rail iServer
For overall dimensions of unit, refer to igure 5.2 in Specifications Section.

6
2.2 DIP Switches
2.2.1 DIP Switch Usage
The iServer is shipped with all DIP switches in "O " position.
1 To change the IP address, gateway address, and subnet mask from the serial port
2 To change to default factory settings
3 To enable/disable DHCP
4 To enable/disable Terminal Server function
To set the iServer to factory default settings, slide DIP switch #2 to ON position.
Power the iServer on and wait about 10 seconds until the iServer fully boots up.
Set the DIP switch #2 back to O position (it does not matter if the iServer is
powered ON or OFF, just make sure that the DIP switch is set to OFF, otherwise,
every time the unit is power-cycled the factory settings will take over.
To enable the DHCP, besides using DIP switch #3, set the iServer’s IP address
to 0.0.0.0. An iServer with IP address of 0.0.0.0 will request an IP address,
gateway address, and subnet mask from the DHCP server over the Ethernet.
igure 2.4a DIP Switch igure 2.4b DIP Switch
Wall Mount iServer DIN Rail iServer
1
4
3
2
OFF
ON
1
4
3
2
OFF
ON
SW1
SW1
OFF
ON
4
3
2
1
SW1
OFF
ON
4
3
2
1
SW1

7
2.3 Parts of the iServer Unit
igure 2.5 Parts of the iServer Unit
Table 2.1 Parts of iServer Unit
SERIAL DB9 male (DTE Configuration) or 2, four position connectors
for RS232 / RS485 connections
ETHERNET RJ45 interface for 10BASE-T connection.
RESET Button: Used for power reseting the iServer.
ACTIVITY LED (Red) Blinking: Indicates network activities (receiving or sending packets).
NET LINK LED (Green) Solid: Indicates good network link.
TX LED (Yellow) Blinking: Indicates transmitting data to the serial port.
RX LED (Green) Blinking: Indicates receiving data on the serial port.
POWER LED (Green) Solid: Indicates Power-ON.
DC Power Supply Section:
+Plus power supply wire connection (inside the plug for -W).
-Minus power supply wire connection (outside the plug for -W).
ACTIVITY
NETWORK LINK
TX-TRANSMIT
RX-RECEIVE
RS-232 / RS-485
SERIAL
RX TX LINK ACT
Mounting Bracket

8
2.4 Serial Communication Interfaces
Two communication interfaces are supported in the iServer: RS232 and RS485. These
standards define the electrical characteristics of a communication network. The RS485
port of the iServer is fully compatible to use with RS485 instruments. The RS485 is an
extended version of the RS422 communication standard which increases the allowable
number of devices from 10 to 32 by improving the electrical characteristics.
• The RS232 standard (point-to-point) allows a single device to be connected to an
iServer. The iServer operates with full-duplex RS232 using eight wires: Rx-receive,
Tx-transmit, DTR, DSR, DCD, CTS, RTS and common ground wires. RS232 cable
length is limited to 50 feet.
• The RS485 standard (multi-point) allows one or more devices (multi-dropped) to be
connected to the iServer using a two-wire connection (half-duplex) +Rx/+Tx and
–Rx/-Tx. Use of RS485 communications allows up to 31 devices to connect to the
iServer with cable length up to 4000 feet long.
Although the RS485 is commonly referred to as a "two wire" connection, the
iServer also provides a ground/return shield connection to use as a common
connection for EMI noise protection.
Table 2.2 shows the differences between RS232 and RS485 communication interfaces.
Table 2.2
Data Transmission RS232 RS485
Characteristics
Transmission Mode Single ended Differential
Electrical connections 8 wire (-W); 7 wire (DIN Rail) 2 wire
Drivers per line 1 driver 32 drivers
Receivers per line 1 receiver 32 receiver
Maximum cable length 50 ft (15 meters) 4000 ft (1200 meters)
Changing between RS232 and RS485 interfaces, as well as modifying the other
parameters is possible through the iServer firmware using its home Web page or
Telnet connection (see Part 4 for details).

9
2.4.1 Wiring RS232 Interface -- Wall Mount iServer
Table 2.3 shows the signals and the direction of signals on the DB9 (DTE configuration)
RS232 Serial Port.
Table 2.3
2.4.2 Wiring RS232 Interface -- DIN Rail iServer
Table 2.4 shows the signals and the direction of signals on the Screw Terminal Block
connector.
Table 2.4
9-12 Vdc
ETHERNET RESET
ACTIVITY
NETWORK LINK
TX-TRANSMIT
RX-RECEIVE
Wall Mount iServer
DB9 Pin# Signal Direction
1 DCD IN
2 Rx IN
3 Tx OUT
*4 DTR OUT
5 GND --
*6 DSR IN
*7 RTS OUT
*8 CTS IN
9 N/C N/C
*These 4 pins can
also be used as
digital input/output
signals (firmware
selection).
DIN Rail iServer
Pin # Signal Direction
1 N/C --
2 GND --
3 Rx IN
4 Tx OUT
*5 DCD IN
*6 RTS OUT
*7 DTR OUT
*8 CTS IN
*These 4 pins can also
be used as digital
input/output signals
(firmware selection).
ACTIVITY
NETWORK LINK
TX-TRANSMIT
RX-RECEIVE
RS-232 / RS-485 / RS-422
SERIAL
RX TX LINK ACT

2.4.3 Wiring RS485 Interface -- Wall Mount iServer
RS485 interface uses a two-wire communication system (one for transmitting and one for
receiving) plus a common wire to connect to the shield of the cable. It is recommended
to use a shielded cable with one twisted pair.
Use of twisted pair and shield will significantly improve noise immunity.
igure 2.6 shows multi-point, half-duplex RS485 interface connections for the iServer.
igure 2.6 Multi-point, Half-Duplex RS485 Wiring - Wall Mount iServer
Value of the termination resistor is not critical and depends on the cable impedance.
Table 2.5 shows RS485 half-duplex hookup between the iServer serial port and device
with RS485 communication interface.
Table 2.5
Pin# iServer DEVICE WITH RS485
2+Tx/+Rx (+Transmit/+Receive) +Tx/+Rx (+Transmit/+Receive)
3-Tx/-Rx (-Transmit/-Receive) -Tx/-Rx (-Transmit/-Receive)
5RTN (Common GND) GND (Common GND)
DEVICE #1 DEVICE #29
DEVICE #31
DEVICE #30
DEVICE #2
iServer
120 Ohm
Termination resistor
GND
-Tx/-Rx
+Tx/+Rx
+Tx/+Rx
-Tx/-Rx
Twisted shielded pair
-Tx/-Rx
-Tx/-Rx-Tx/-Rx
-Tx/-Rx
+Tx/+Rx
+Tx/+Rx
GND
GND
GND
GND
+Tx/+Rx
+Tx/+Rx
.........................
.........................
...............................
...............................
23
5
120 Ohm
Termination resistor
10
10

2.4.4 Wiring RS485 Interface -- DIN Rail iServer
RS485 interface uses a two-wire communication system (one for transmitting and one for
receiving) plus a common wire to connect to the shield of the cable. It is recommended
to use a shielded cable with one twisted pair.
Use of twisted pair and shield will significantly improve noise immunity.
igure 2.7 shows multi-point, half-duplex RS485 interface connections for the iServer.
igure 2.7 Multi-point, Half-Duplex RS485 Wiring - DIN Rail iServer
Value of the termination resistor is not critical and depends on the cable impedance.
Table 2.6 shows RS485 half-duplex hookup between the iServer serial port and device
with RS485 communication interface.
Table 2.6
Pin# iServer DEVICE WITH RS485
3+Tx/+Rx (+Transmit/+Receive) +Tx/+Rx (+Transmit/+Receive)
4-Tx/-Rx (-Transmit/-Receive) -Tx/-Rx (-Transmit/-Receive)
2RTN (Common GND) GND (Common GND)
DEVICE #1 DEVICE #29
DEVICE #31
DEVICE #30
DEVICE #2
iServer
120Ohm
Termination resistor120Ohm
Termination resistor
GND
-Tx/-Rx
+Tx/+Rx
+Tx/+Rx
-Tx/-Rx
Twistedshieldedpair
-Tx/-Rx
-Tx/-Rx-Tx/-Rx
-Tx/-Rx
+Tx/+Rx
+Tx/+Rx
GND
GND
GND
GND
+Tx/+Rx
+Tx/+Rx
.........................
.........................
...............................
...............................
COMMUNICATIONS
ETHERNET
DCPOWER IN
RXTXLINKACT
RESET
+-N/C
11

2.5 Network Communication Interfaces
2.5.1 10Base-T RJ-45 Pinout
The 10BASE-T Ethernet network (RJ-45) system is used in the iServer for network
connectivity. The 10 Mbps twisted-pair Ethernet system operates over two pairs of wires.
One pair is used for receiving data signals and the other pair is used for transmitting data
signals. This means that four pins of the eight-pin connector are used.
igure 2.8 RJ45 Pinout
2.5.2 10Base-T Crossover Wiring
When connecting the iServer directly to the computer, the transmit data pins of the
computer should be wired to the receive data pins of the iServer, and vice versa. The
10Base-T crossover cable with pin connection assignments are shown on igure 2.9.
igure 2.9 10Base-T Crossover Cable Wiring
Use straight through cable for connecting the iServer to an Ethernet hub. The ports on
the hub are already crossed.
12
Pin Name Description
1 +Tx + Transmit Data
2 -Tx - Transmit Data
3 +RX + Receive Data
4 N/C Not Connected
5 N/C Not Connected
6 -Rx - Receive Data
7 N/C Not Connected
8 N/C Not Connected

13
PART 3
NETWORK CONFIGURATION
3.1 Network Protocols
The iServer can be connected to the network using standard TCP/IP protocols.
It also supports ARP, HTTP (WEB server), DHCP, DNS and Telnet protocols.
3.2 Ethernet (MAC) Address
MAC (Media Access Control) address is your computer's unique hardware number.
When you're connected to the LAN from your computer, a correspondence table relates
your IP address to your computer's physical (MAC) address. The MAC address can be
found on the label of your device and contains 6 bytes (12 characters) of hexadecimal
numbers XX:XX:XX:XX:XX:XX hex
or example: 0A:0C:3D:0B:0A:0B
Remove the small label with the default IP address and there will be room to put
your IP address. See igure 3.1
igure 3.1 Labeling
#.#
MODEL NO:
SERIAL NO:
INPUT POWER:
IP:
MODEL NO:
SERIAL NO:
INPUT POWER:
IP:
#.#
MAC ADDRESS
LABEL IN
HEX CODE
REMOVE DEFAULT
IP ADDRESS LABEL
AND PUT NEW
CUSTOMER'S
IP ADDRESS
iSERVER'S VERSION #
MAC ADDRESS
LABEL IN
HEX CODE
iSERVER'S VERSION #
REMOVE DEFAULT IP
ADDRESS LABEL AND PUT
NEW CUSTOMER'S
IP ADDRESS

3.3 DHCP
DHCP, Dynamic Host Configuration Protocol enables individual computers or devices to
extract their IP configurations from a server (DHCP server). If the DHCP is enabled on
your iServer, as soon as the iServer is connected to the network, there is an exchange of
information between DHCP server and the iServer. During this process the IP address,
the Gateway address, and the Subnet Mask will be assigned to the iServer by the DHCP
server. Note that the DHCP server must be correctly configured to make such assignment.
If fixed or static IP address is desired, the DHCP must be disabled. The iServer is
shipped with DHCP disabled (factory default). The DHCP can be enabled by setting the
DIP switch # 3 to the “ON” position (refer to igure 3.2).
DIP switch # 3 shown in “ON” position
igure 3.2 DIP Switch on the Bottom Side of iServer
Setting the iServer’s IP address to 0.0.0.0 will also enable DHCP.
3.4 DNS
DNS, Domain Name System enables individual computers and devices to be recognized
over a network based on a specific name instead of an IP address. For example, instead
of having to use http://192.168.1.200 (IP address), you would use only http://eis03ec or
any eight character name stored as Host Name under Access Control page in the
iServer Home Page. The default DNS name for an iServer is "eis" followed by the last
four digits of the MAC address of that particular iServer.
1. It is very important to communicate with the network administrator in order to
understand the DHCP and its existing configurations on the host server,
before enabling the DHCP on the iServer.
2. The iServers are shipped with a default static IP address of
192.168.1.200 and Subnet Mask of 255.255.255.0.
3. On Novell networks or Windows 2000 where the DCHP is an updated
function of DNS this feature may be beneficial since a particular name can be
assigned eliminating the need for the IP address, as described in Section 3.4.
3.5 IP Address
Every active device connected to the TCP/IP network must have a unique IP address.
This IP address is used to build a connection to the iServer’s serial port. Every computer
using TCP/IP should have a unique 32-bit address. It is divided into two portions, the
network ID and the host ID. For instance, every computer on the same network uses the
same network ID. At the same time, all of them have a different host ID. For more details
about the IP address see Appendix B.
OFF
ON
4
3
2
1

OFF
ON
4
3
2
1

14