CTI 2500-RIO-B Operating instructions

CTI 2500-RIO-B
RS485 REMOTE BASE CONTROLLER
INSTALLATION AND OPERATION GUIDE
Version 1.4
2500-RIO-B-IOG/04242018

CTI 2500-RIO-B Installation and Operation Guide V1.4
Copyright © 2018 Control Technology Inc.
All rights reserved.
This manual is published by Control Technology Inc., 5734 Middlebrook Pike, Knoxville, TN 37921.
This manual contains references to brand and product names which are trade names, trademarks,
and/or registered trademarks of Control Technology Inc. Siemens® and SIMATIC® are registered
trademarks of Siemens AG. Other references to brand and product names are trade names,
trademarks, and/or registered trademarks of their respective holders.
DOCUMENT DISCLAIMER STATEMENT
Every effort has been made to ensure the accuracy of this document; however, errors do occasionally
occur. CTI provides this document on an “as is” basis and assumes no responsibility for direct or
consequential damages resulting from the use of this document. This document is provided without
express or implied warranty of any kind, including but not limited to the warranties of
merchantability or fitness for a particular purpose. This document and the products it references are
subject to change without notice. If you have a comment or discover an error, please call us toll-free
at 1-800-537-8398 or email us at [e-mail].
REVISION HISTORY
V1.0
07/10/13
Original Issue
V1.1
9/4/13
Add Alternate wiring diagram and cable specs
V1.2
5/27/2014
Changed “JP1” references to “JP4” to correct error
V1.3
9/9/2014
Added Immediate and Interrupt IO Note in Section 1.1
V1.4
4/24/2018
Added “Note: Addresses above STW242 are used only by CTI’s 2500
Series® CPU’s. ” in Section 2.9. pdb

CTI 2500-RIO-B Installation and Operation Guide V1.4
PREFACE
This Installation and Operation Guide provides reference information for the CTI 2500-RIO-B
RS485 Remote Base Controller. The information in this manual is directed to individuals who will
be installing the module and configuring it for use with a CTI 2500 Series® or Simatic® 505
Processor.
We assume you are familiar with the installation and operation of:
2500 Series® programmable controllers
Please refer to the appropriate SIMATIC® user documentation for specific information on
SIMATIC® 505 programmable controllers and I/O modules.

CTI 2500-RIO-B Installation and Operation Guide V1.4
USAGE CONVENTIONS
NOTE:
Notes alert the user to special features or procedures.
CAUTION:
Cautions alert the user to procedures that could damage equipment.
WARNING:
Warnings alert the user to procedures that could damage equipment and endanger the user.

CTI 2500-RIO-B Installation and Operation Guide V1.4
TABLE OF CONTENTS
CHAPTER 1. DESCRIPTION ___________________________________________________ 3
1.1. Introduction _______________________________________________________________ 3
1.2. Communication Ports_____________________________________________________ 4
1.2.1. Serial Port _______________________________________________________________________ 4
1.2.2. I/O Port _________________________________________________________________________ 4
1.3. Dual-Media and Hardware Redundancy Installations ______________________________ 4
1.3.1. Resetting Standby RBC after Communications Loss ______________________________________ 4
1.3.2. Typical Installation of Redundant Remote Bases ________________________________________ 5
1.3.3. Recommended Installation of Redundant Remote Bases __________________________________ 6
CHAPTER 2. INSTALLATION __________________________________________________ 7
2.1. Installation Planning______________________________________________________ 7
Choosing Remote I/O Media _____________________________________________________________ 7
Selecting a Remote Base Address__________________________________________________________ 7
Setting Module Hardware Options_________________________________________________________ 7
Connecting to Remote I/O Cable __________________________________________________________ 7
2.2. Power Requirements _____________________________________________________ 7
2.3. Unpacking the Module _______________________________________________________ 8
2.4. Configuring the Module ______________________________________________________ 8
Setting the RS232 Port Baud Rate _________________________________________________________ 8
Setting Remote Base Controller Station Address______________________________________________ 8
Setting the Output State on Communication Loss_____________________________________________ 9
2.5. Physical Installation ________________________________________________________ 10
2.6. Connecting to the RS232 Port ________________________________________________ 10
2.7. Connecting the Remote I/O Cable _____________________________________________ 11
2.8. Operation of LED Display ____________________________________________________ 12
2.9. System Status Words _______________________________________________________ 13
APPENDIX A. REMOTE I/O INSTALLATION GUIDELINES __________________________ 14
Cable Layout Planning__________________________________________________________________ 14
Cable Selection _______________________________________________________________________ 14
Alternatively, Beldon 9860, 9271, and 9182 cable can be used to wire your remote I/O. The table below
gives the cable specifications for these models. ______________________ Error! Bookmark not defined.
Cable Lengths ________________________________________________________________________ 16
Bus termination_______________________________________________________________________ 18
Laying Cables Outside of Control Cabinets _________________________________________________ 19
APPENDIX B. I/O “SAFE STATE” OPERATION ___________________________________ 20

CTI 2500-RIO-B Installation and Operation Guide V1.4
SPECIFICATIONS __________________________________________________________ 21
General _____________________________________________________________________ 21
Ports _______________________________________________________________________ 21
Environmental_______________________________________________________________ 21
LIMITED PRODUCT WARRANTY______________________________________________ 22
REPAIR POLICY ___________________________________________________________ 23

CTI 2500-RIO-B Installation and Operation Guide V1.4
3
CHAPTER
1.
DESCRIPTION
1.1. Introduction
The CTI 2500-RIO-B RS485 Remote Base Controller is
a member of Control Technology's family of I/O
modules compatible with programmable controllers
from Siemens® and CTI.
The 2500-RIO-B RS485 Remote Base Controller (RBC)
allows a 2500 Series® I/O base to function as a remote
base. The 2500-RIO-B is intended to be a replacement
for the Siemens® 505-6851-A RBC. It provides the
following functions:
Compatible with CTI 2500 Series® and
Simatic® 505® CPUs.
Can be used in currently-available CTI and
Siemens® 4, 8, 11, and 16-slot bases
Supports communication speeds 1Mbits/sec and
maximum cable distance of 1000 meters
LED display which shows error and status codes
Front panel thumbwheel switch for setting the
station address
On-board RS232 port which can be used for
PLC programming and configuration.
The 2500-RIO-B resides in 2500 Series® base. It
installs in the second slot from the left, adjacent to the
power supply module. When used in a 2500-R11-A
Redundant Base, two 2500-RIO-B units can be installed
in the third and fourth slots from the left, adjacent to the
second power supply.
Do not install this module into a normal I/O slot, as damage can occur.
NOTE:
Immediate IO and Interrupt IO are not supported by the RS-485 Remote IO Network System.
Figure 1. 2500-RIO-B Front Panel

CTI 2500-RIO-B Installation and Operation Guide V1.4
4
1.2. Communication Ports
The 2500-RIO-B RS485 RBC has two communication ports on the front panel.
1.2.1. Serial Port
The RS232 port is provided to interface to PLC programming and configuration tools such as
TISOFTTM. A standard 9-pin PC-compatible RS232 serial cable is used to connect to the
programming device or modem. The port pinout is provided in Section 2.6 of this manual.
1.2.2. I/O Port
The I/O Port connects the 2500-RIO-B to a SIMATIC® 505 compatible RS485 Remote I/O
channel. This enables the remote CPU to control the I/O modules in the base where the RBC
is located.
The Remote I/O Port interface is a 9-pin D-Shell connector as detailed in Section 2.7 of this
manual. Recommended guidelines for planning, selection, and installation of Remote I/O
system is included in Appendix A.
1.3. Dual-Media and Hardware Redundancy Installations
A pair of 2500-RIO-B RBC’s may be installed in a 2500-R11-A or 505-6511 redundant base to
provide dual media as well as hardware redundancy. In a redundant configuration, two 2500-RIO-B
units are installed in the base and separate cable runs are used to provide redundancy in both the
hardware and communications cabling between the CPU and the remote base. The dual RBCs
function in an active/standby configuration. A loss of communications to the active RBC will result
in switching to the standby RBC with no change to system outputs.
NOTE
For dual media installations, the 2500-RIO-B must be at firmware revision 7.03 or higher, and the
2500 Series® Processor must be at firmware V6.17 or higher.
1.3.1. Resetting Standby RBC after Communications Loss
In the event of communications failure in the primary RBC, the primary RBC will go into failure
mode and the LED display will go from a [0] to a [1]. A soon as the RBC detects the communication
failure, the secondary RBC will become active and the LED display will go from a [C] to a [0]. The
LED status codes are [C]=standby, [0]=active, and [1]=failure.
After resolving the communications problem, the backup RBC must be returned to “standby” status.
This is accomplished by moving the thumbwheel address switch to a different address and then back
to the desired address. The backup RBC will then be reconfigured and placed back in “standby”
mode.

CTI 2500-RIO-B Installation and Operation Guide V1.4
5
T
T
2500-TAP
T
Termination
2500-TAP
1.3.2. Typical Installation of Redundant Remote Bases
Pictured in figure 1 is an example of a typical hardware and cabling layout for achieving dual media
redundancy. The 2500-Tap RS-485 Remote I/O Tap and Terminator is required for dual media
applications.
NOTE
Only 2500-RIO-A or 2500-RIO-B controllers may be used in redundant or dual media applications.
CTI RIO modules cannot be combined with Siemens 505-6851A or 505-6851B modules.
NOTE
For comprehensive remote I/O system design and installation information, you should also obtain the
CTI 2500 Series® Remote I/O System Design, Installation & Troubleshooting Guide available for
download on the Control Technology Website. www.controltechnology.com
Local Base
Figure 1: Typical Dual Media Redundancy Layout
A
B
A
B
Remote Bases
KEY

CTI 2500-RIO-B Installation and Operation Guide V1.4
6
T
T
RIO Connector –
Phoenix Contact
T
Termination
Poenix Contact
#2761826
1.3.3. Recommended Installation of Redundant Remote Bases
Pictured in figure 2 is an example of the recommended hardware and cabling layout for achieving
optimum dual media redundancy. The recommended RIO connector is made by Phoenix Contact and
the model number is 2761826.
Termination resistors must be installed at the ends of the trunk line, as shown in figure 2. The resistor
value required depends on the trunk cable as specified in the table below:
Cable Type
Resistor Value
Belden®3105A
120 ohms, 5%, ¼ W
Belden®9182
150 ohms, 5%, ¼ W
Belden®9860 or 9271
120 ohms, 5%, ¼ W
The terminating resistor is installed between terminal numbers 3 and 8, the transmit and receive
lines.
Local Base
Figure 2: Recommended Dual Media Redundancy Layout
A
B
A
B
Remote Bases
KEY

CTI 2500-RIO-B Installation and Operation Guide V1.4
7
CHAPTER 2. INSTALLATION
The installation of the Model 2500-RIO-B RS485 Remote Base Controller consists of the following
steps:
1) Planning the installation
2) Verifying power requirements
3) Unpacking and configuring the module
4) Physical installation
5) Connecting cables
6) Checking the module operation
2.1. Installation Planning
Choosing Remote I/O Media
The 2500-RIO-B attaches directly to the RS485 Remote I/O cable using a DB9 connector. We
recommend using cable designed specifically for RS485 systems, such as Belden 3105A. See
Appendix A for information related to cable specifications, layout, and installation.
Selecting a Remote Base Address
Before proceeding, you must determine what address you will assign to the RBC. Remote Base
addresses range from 1 to 15. In CTI 2500 Series® and Simatic® 505® systems, address 0 is
reserved for the local base where the CPU is installed. Note that each Remote Base on the Remote
I/O channel must have a unique address. If two RBCs are installed in a 2500-R11-A Redundant
Base, they must both be set to the same address.
Setting Module Hardware Options
The RBC includes a hardware setting for selecting the state of the base discrete outputs in the event
of a loss of communication with the CPU. The module can be configured to set all outputs off, or to
leave outputs at their last states. If two RBCs are installed in a 2500-R11-A Redundant Base, they
must both have the same configuration.
Connecting to Remote I/O Cable
The Remote I/O connector should be wired as shown in Section 2.7.
2.2. Power Requirements
The CTI 2500-RIO-B module consumes 2.5 watts of +5 VDC power from the backplane. Before
installing the RBC, verify that your mounting base power budget can accommodate the required
power. A good tool for performing the verification is the CTI Replacement Guide and Power
Calculator, available from our website at
ftp://ftp.controltechnology.com/public/Download/tools/

CTI 2500-RIO-B Installation and Operation Guide V1.4
8
2.3. Unpacking the Module
Open the shipping carton and remove the special anti-static bag that contains the module.
After discharging any static build-up, remove the module from the static bag. Do not discard the
static bag. Always use this bag for protection against static damage when the module is not inserted
into the I/O base.
CAUTION:
The components on the 2500-RIO-B module printed circuit card can be damaged by static
electricity discharge. To prevent this damage, the module is shipped in a special anti-static
bag. Static control precautions should be followed when removing the module from the bag
and when handling the printed circuit card during configuration.
2.4. Configuring the Module
There are three steps to configuring the module and making it fully operational:
1. Setting the RS232 Port baud rate
2. Setting the Remote Base Controller address
3. Setting the output state on communication loss
(Freeze Jumper)
Figure 2 indicates the location of the RS232 port baud
rate selection switches, the RBC station address
thumbwheel, and Freeze Jumper. The remainder of this
section describes the function of the individual settings.
Setting the RS232 Port Baud Rate
Switches SW1-SW4 are used for setting the baud rate
of the RS-232 serial port. The supported baud rates are
shown in the following table. All other switch
combinations are invalid.
Baud Rate
SW1
SW2
SW3
SW4
19200
1
1
0
1
9600
1
1
1
1
2400
0
1
1
1
1200
1
0
1
1
300
0
0
1
1
Figure 2. Switch Locations
Baud Rate
Selection Switches
Freeze Jumper
RBC Station
Address

CTI 2500-RIO-B Installation and Operation Guide V1.4
9
Setting Remote Base Controller Station Address
A thumbwheel switch is provided to set the base address to the 2500-RIO-B for Remote I/O station
identification. A maximum of 15 remote bases can be connected to the CTI 2500 Series® CPU or
Siemens® 545/555/575 CPU.
NOTE:
When connecting the 2500-RIO-B to a CTI 2500 Series® CPU or Siemens® 545/555/575 CPU, only
addresses between 1 and 15 are valid. Each installed 2500-RIO-B must have a unique station
number.
Care should be taken to prevent circumstances which cause the CPU to lose communication with the
2500-RIO-B while the system is operating. Loss of communication between the CPU and RBC will
cause the base to be logged off from the CPU. This can cause intermittent process operation.
WARNING:
The following events will cause loss of communication with the 2500-RIO-B and result in the
base being logged off from the CPU.
1) Duplication of the station address between RBC’s attached to the same CPU
(except in dual-media applications).
2) Changing the thumbwheel switch station address while the system is operating.
These events could cause unpredictable process operation and result in damage to equipment
and/or serious injury to personnel.
When a base is logged off, the CPU zeroes all image register input points associated with the base
and all outputs go to the value determined by the installed output module. Discrete outputs turn OFF
(0) and Analog/Word outputs are set according to the Zero/Hold Last Value settings in each
particular module. Your program can monitor the CPU Status Words to detect this condition and
control the outputs from other remote bases as appropriate for the application. Details on the Status
Words and programming examples can be found in the SIMATIC® 545/555/575 Programming
Reference User Manual.
Setting the Output State on Communication Loss
When I/O channel communication to a remote base is lost, the state of the discrete outputs is
determined by the selection made on the 2500-RIO-B jumper JP4 (Off/Freeze). Figure 2 shows the
location of the jumper on the 2500-RIO-B.
NOTE:
The 2500-RIO-B ships with the FREEZE jumper in the OFF setting.
If the jumper JP4 is missing from the board, the 2500-RIO-B defaults to the OFF setting.
For discrete output modules, the state of the outputs is determined solely by the position of the
Off/Freeze jumper JP4 on the 2500-RIO-B.

CTI 2500-RIO-B Installation and Operation Guide V1.4
10
For analog/word output modules, the state of the outputs is influenced not only by the position of the
Off/Freeze jumper but by the output module’s (Zero/Hold Last Value) selection, if the module has
that option. See the table below.
RBC Off/Freeze
Selection
Analog/Word Module
Zero/Hold Selection
Analog/Word Output
State
Off
Zero
Zero*
Off
Hold Last Value
Last Value
Off
No selection
Last Value
Freeze
Zero
Last Value
Freeze
Hold Last Value
Last Value
Freeze
No selection
Last Value
*see the user manual of your analog/word output module for details
Notice that the FREEZE option on the RBC overrides the Zero selection on the analog/word output
module; likewise, when Hold Last Value is selected on the analog/word output module, that selection
overrides the OFF option on the RBC jumper.
WARNING:
If the RBC fails or loses power during system operation, all outputs will turn OFF(0) regardless
of the Freeze Jumper setting. This could result in damage to equipment and/or serious injury
to personnel.
2.5. Physical Installation
To insert the module into the I/O base, hold the top and bottom of the bezel and slide the module
carefully into the slot, pushing it all the way into the base. If you have inserted the module correctly,
you will feel a slight increase in resistance as the module mates with the base backplane connector.
Once the module is fully seated in the slot, tighten the captive screws at the top and bottom to hold
the module in place. To remove the module from the I/O base, loosen the captive screws, and then
pull the module from the base. Take care not to damage the connector at the back of the module
when inserting or removing the module.
2.6. Connecting to the RS232 Port
The RS232 port is provided to interface to PLC programming and configuration tools such as
TISOFTTM. The use of this port is optional. A standard 9-pin PC RS232 serial cable can be used to
connect to the programming device or modem. The port details are shown in Figure 3. Note that
the serial port on the standby unit in a redundant RBC pair is inoperative. This is normal –
the CPU makes no attempt to communicate with the serial port of the standby RBC. The
standby unit is the one displaying a “C” on the front panel LED display.

CTI 2500-RIO-B Installation and Operation Guide V1.4
11
5
9
61
9-Pin D-Shell Male Connector
Compatible with standard PC Serial Port
SGND (5)
RxD (2)
TxD (3)
DCD (1)
DTR (4)
DSR (6)
RTS (7)
CTS (8)
Figure 3. RS232 Serial Port
2.7. Connecting the Remote I/O Cable
The I/O Port connects the 2500-RIO-B to a SIMATIC® 505 compatible RS485 Remote I/O
channel. This enables the remote CTI 2500 Series® or Simatic® 505® CPU to control the I/O
modules in the base where the RBC is located.
The Remote I/O Port interface is a 9-pin D-Shell connector with pinout as shown in Figure 3.
Recommending wiring for the Remote I/O cabling is detailed in Siemens® 545/555/575 System
Manual. Figure 4 shows the pinout for the I/O Port.
5
9
61
TX/RX- (8) TX/RX+ (3)
GND (5)
9-Pin D-Shell Female Connector
Figure 4. Remote I/O Port

CTI 2500-RIO-B Installation and Operation Guide V1.4
12
2.8. Operation of LED Display
The LED Display is used to indicate the status of the 2500-RIO-B Remote Base Controller as shown
in the following table:
Display
Definition
Communications
to RBC
Comment / Action
0
Module Ready
OK
Fully Operational and online with CPU.
1
Diagnostics Failure
None
Serious malfunction. Place system in safe
state and contact CTI Technical Support.
2
Module Mismatch
OK
I/O modules installed do not match the
expected configuration in the CPU.
3
I/O Communications
timeout
Failed
There is no communication with the CPU.
Place the system in a safe state. Check
power, cabling, and connection to the CPU.
4
Ram Parity Error
Failed
Serious malfunction. Place system in safe
state and contact CTI Technical Support.
5
Standby, No
Configuration
None
Standby RBC in dual-media application is
not configured. Configure module.
6
Address Mismatch
OK
Dual-media RBC’s must have identical
station address. If addresses are equal,
contact CTI Technical Support.
7
Communications OK,
No Configuration
OK
2500-RIO-B is not configured. Configure
RBC in CPU.
8
Watchdog timeout
Failed
Serious malfunction. Place system in safe
state and contact CTI Technical Support.
*blank*
No Code Displayed
None
Serious condition. 2500-RIO-B is not
operational. If power to base is OK, contact
CTI Technical Support.
C
Standby unit
configured
OK
Standby unit of a redundant pair is
configured and communicating
A,B,E
Internal Failure
Failed
Hardware failure detected during power on
initialization tests.
Following power up of a redundant RBC pair, the unit on the left becomes the primary and displays a
“0”. The unit on the right becomes the standby unit and displays a “C”.

CTI 2500-RIO-B Installation and Operation Guide V1.4
13
2.9. System Status Words
There are a number of system status words which are important in observing remote I/O system
operation and isolating problems. If you are experiencing remote I/O problems, you should pay
careful attention to the following status words.
STW2 Base controller status
STW11-26 I/O module status
STW145 Remote I/O receive errors
STW146 Remote I/O timeout errors
STW168 Dual RBC Status
STW184 I/O module mismatch
STW210 Remote I/O base poll enable flags
Note: Addresses above STW242 are used only by CTI’s 2500 Series® CPU’s.
STW455-461 Remote base receive errors
STW471-485 Remote base abnormal logoff counts
STW487-501 Remote base timeout counts
More complete information and a list of the 2500 Series® Processor System Status Words can be
found in the 2500 Series® Processor Installation and Operation Guide:
http://www.controltechnology.com/Files/Products/2500-(Classic)/2500-Cxxx/manuals/CTI-2500-
IOG-(62-370)

CTI 2500-RIO-B Installation and Operation Guide V1.4
14
APPENDIX A. REMOTE I/O INSTALLATION GUIDELINES
These Remote I/O Installation Guidelines are based on standard RS485 wiring practices. See
Chapter 6 of the SIMATIC® 505 545/555/575 System Reference Manual for further details.
The Remote I/O cable system consists of a main trunk line and drop lines which connect the
CPU/Local Base and Remote Base(s) to the trunk line by means of terminal blocks as shown in
Figure 5.
Local Base
T TT
Remote Base Remote Base
Trunk Lines
Drop Lines
Drop Line
T = Terminal Block
Figure 5. Remote I/O Installation
Cable Layout Planning
Use the following guidelines for planning the Remote I/O cable routing and locations:
•The ideal cable installation is a single, unbranched trunk line with short drop lines and
termination resistor at each end
•Maximum length of a drop line should not exceed 33 feet (10 m)
•Drop lines less than 3.3 feet (1 m) do not count toward cable length calculations
•The total length of all drop lines should be much less than the length of the trunk line
•When multiple bases must be located in close proximity, connect all bases in a “daisy-chain”
arrangement with a single drop line.
Cable Selection
Data transfer in the Remote I/O systems is based on a symmetrical RS485 bus system using shielded
twisted pair cable. The cable shield is used to improve the immunity to electromagnetic interference.
The ideal cable provides low signal attenuation for long trunk lines and flexibility for ease of
installation. The recommended cable should include the characteristics as shown in the following
table.

CTI 2500-RIO-B Installation and Operation Guide V1.4
15
CTI recommends Beldon 3105A cable for wiring remote I/O. The following table contains the
general recommended cable specs for RS485 remote I/O wiring and the preferred Beldon cable type
specifications.
Cable Characteristic
Recommended
Belden® 3105A
Conductors
18AWG to 22AWG uniform
twisted-pair
2-conductors,22AWG,.030
in (7.5mm), 7x30 stranded
Shielding
100% shield coverage
100% coverage with 90%
copper braid plus drain wire
Characteristic
Impedance
100 Ωto 150 Ω
120 Ω
Capacitance
< 50 pF/m
11 pF/ft (36 pF/m)
DC Resistance
Resistance of installed length
< characteristic impedance
14.7 Ω/1000 ft (48.2 Ω/km)
Attenuation
< 1.0 dB/100 ft
(1.0 dB/ 30 m)
0.5 dB/100 ft (0.5 db/30 m)
@ 1MHz
Velocity of
Propagation
> 65%
78%
Operating Temperature
0 to +60 ºC
-20 to +60 ºC
2.3 Specify Cable Type
Based on your topology selection and distances, specify the cable type to be used based on the
information included below. The following cables (or equivalent) are acceptable for use for remote
I/O connections.
Alternative Cable Specs
Belden
Cable Type
Outside
Diameter
Impedance
Capacitance
Velocity
Center
Conductor
3105A
.281 in
7.1 mm
120 ohm
36 pf/m
0.78c
22 AWG 7x30
48.2 ohm/km
9182
0.35 in.
8.9 mm
150 ohm
28.9 pf/m
0.78c
22 AWG 19x34
46 ohm/km
9271
0.24 in
6.1 mm
124 ohms
40 pf/m
0.66c
25 AWG 7x33
104.3 ohm/km
9860
0.44 in.
11.2.mm
124 ohms
35.8 pf/m
0.78c
16 AWG Solid
13.8.ohm/km
Belden 9182 and 3105A are suitable for intermediate length trunk lines. These cables cannot be
intermixed with other cables for trunk lines. In addition, if either of these cables are used for a trunk
line, they must also be used for all drop lines. They may also be used for drop lines with Belden
9860 or Belden 9271 trunk lines.

CTI 2500-RIO-B Installation and Operation Guide V1.4
16
Belden 9271, which is smaller and more flexible, is suitable for use as drop lines as well as short
trunk lines. For trunk lines, this cable may be intermixed with Belden 9860.
Belden 9860 cable, which provides low attenuation and distortion, should be used for long trunk
lines.
NOTE: If the trunk line is Belden 9182, then the droplines must also be Belden 9182. If the trunk
line is Belden 3105A, 9860, or 9271, then the droplines can be 3105A, 9271, or 9182.
If you use cable types other than these, you should ensure the following requirement are met:
Characteristic impedance between 100 and 150 ohms (124 ohms optimum) High uniform twist
and spacing of conductors (twinaxial cable) Shield coverage approaching 100% DC resistance
smaller than the characteristic impedance Jacket suitable for the installation
Cable Lengths
Maximum permissible cable length is dependent on cable characteristics and number of terminal
blocks used in the installation. Terminal blocks are used to connect drop lines and/or extend Remote
I/O cable trunk line. The following table contains the maximum recommended cable length (Trunk
Length + Drop Lines) for Belden® 3105A cable. It is possible to have longer cable runs if larger
diameter wire is used.
Number of Installed
Drop Lines
Maximum Cable Length in
Feet (Meters)
Belden 3105A
2-5
2200 (670)
6
2133 (650)
7
2067 (630)
8
2000 (610)
9
1933 (589)
10
1867 (569)
11
1800 (548)
12
1733 (528)
13
1667 (508)
14
1600 (488)
15
1533 (467)
16
1467 (447)
17
1400 (427)