IEC 60728-7-3:2009

IEC 60728-7-3 ®
Edition 2.0 2009-10
INTERNATIONAL
STANDARD
colour
inside
Cable networks for television signals, sound signals and interactive services –
Part 7-3: Hybrid fibre coax outside plant status monitoring – Power supply to
transponder interface bus (PSTIB)

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IEC 60728-7-3 ®
Edition 2.0 2009-10
INTERNATIONAL
STANDARD
colour
inside
Cable networks for television signals, sound signals and interactive services –
Part 7-3: Hybrid fibre coax outside plant status monitoring – Power supply to
transponder interface bus (PSTIB)

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
PRICE CODE
W
ICS 33.040; 33.160 ISBN 978-2-88910-263-1
– 2 – 60728-7-3 © IEC:2009(E)
CONTENTS
FOREWORD.5
INTRODUCTION.7
1 Scope.8
2 Normative references .9
3 Terms, definitions and abbreviations .9
3.1 Terms and definitions .9
3.2 Abbreviations .10
4 Reference architecture forward and return channel specifications .10
5 Power supply to transponder interface bus specification overview .11
5.1 General .11
5.2 Interface compliance .11
5.3 Implementation compliance .11
5.4 Revision control .12
6 Power supply to transponder interface bus – Physical layer specification .12
6.1 Interface requirements .12
6.1.1 Connector type .12
6.1.2 Communications interface .12
6.1.3 Connector signals.12
6.1.4 Transponder power.12
6.1.5 Line balance.13
6.1.6 Cable length .13
6.1.7 Data encoding .13
6.1.8 Bit rate .13
6.1.9 Duplex.13
6.1.10 Method of communications .13
6.1.11 Indicators .13
6.2 Interface diagram .14
7 Alternative power supply to transponder interface bus – Physical layer
specification .15
7.1 Introduction to alternative.15
7.2 Interface requirements .15
7.2.1 Connector type .15
7.2.2 Communications interface .15
7.2.3 Connector signals.15
7.2.4 Transponder power.15
7.2.5 Line balance.16
7.2.6 Cable length .16
7.2.7 Data encoding .16
7.2.8 Bit rate .16
7.2.9 Duplex.16
7.2.10 Method of communication.16
7.2.11 Indicators .17
7.3 Interface diagram .17
8 Power supply to transponder interface bus – Data link layer specification.18
8.1 DLL packet structure .18

60728-7-3 © IEC:2009(E) – 3 –
8.1.1 General .18
8.1.2 Start .18
8.1.3 Destination Address .18
8.1.4 Source Address .19
8.1.5 Identification.19
8.1.6 Datagram .19
8.1.7 End .19
8.1.8 Checksum .19
8.2 DLE sequence.19
8.3 Interface timing .20
8.3.1 Message synchronization and interaction .20
8.3.2 Transmission timing requirements .21
8.4 DLL datagrams.22
8.4.1 Structure .22
8.4.2 Resolution versus accuracy .23
8.4.3 DLL datagram types .23
Annex A (informative) HMS specification documents.37
Bibliography.38

Figure 1 – Reference architecture diagram .11
Figure 2 – Sample PSTIB RS-485 interface .14
Figure 3 – Sample PSTIB RS-485 interface .17
Figure 4 – DLL packet structure .18
Figure 5 – PSTIB data and timing diagram.21
Figure 6 – DLL datagram structure.22
Figure 7 – Battery string naming conventions.33

Table 1 – Transponder type classifications .8
Table 2 – RJ-45 Connector pin assignment.12
Table 3 – Sample PSTIB RS-485 interface – Reference signals.14
Table 4 – RJ-45 Connector pin assignment.15
Table 5 – Sample PSTIB RS-485 interface – Reference signals.17
Table 6 – Generic DLL packet structure .18
Table 7 – Reserved destination address ranges.19
Table 8 – PSTIB timing specifications .21
Table 9 – Generic DLL datagram structure.22
Table 10 – DLL datagrams.24
Table 11 – Command: Get_Configuration datagram.24
Table 12 – Response: Get_Configuration datagram .25
Table 13 – Response: Get_Configuration datagram variable binding (general).25
Table 14 – Response: Get_Configuration datagram variable binding (power supply).26
a
Table 15 – Response: Get_Configuration datagram variable binding (generator) .29
Table 16 – Command: Get_Power_Supply_Data datagram .30
Table 17 – Response: Get_Power_Supply_Data datagram .30
Table 18 – Response: Get_Power_Supply_Data datagram variable binding.30

– 4 – 60728-7-3 © IEC:2009(E)
Table 19 – Command: Power_Supply_Control datagram.33
Table 20 – Command: Get_Generator_Data datagram.33
Table 21 – Response: Get_Generator_Data datagram .34
Table 22 – Response: Get_Generator_Data Datagram variable binding .34
Table 23 – Command: Generator_Control datagram .35
Table 24 – Response: Invalid_Request datagram .35
Table 25 – Response: Request_Processed datagram .36
Table A.1 – HMS document family .37

60728-7-3 © IEC:2009(E) – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
CABLE NETWORKS FOR TELEVISION SIGNALS,
SOUND SIGNALS AND INTERACTIVE SERVICES –

Part 7-3: Hybrid fibre coax outside plant status monitoring –
Power supply to transponder interface bus (PSTIB)

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote interna-
tional co-operation on all questions concerning standardization in the electrical and electronic fields. To this
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tions.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of pat-
ent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60728-7-3 has been prepared by technical area 5: Cable networks
for television signals, sound signals and interactive services, of IEC technical committee 100:
Audio, video and multimedia systems and equipment.
This second edition cancels and replaces the first edition published in 2003 of which it consti-
tutes a technical revision. This edition includes the following significant technical changes
with respect to the previous edition:
• All changes from standard ANSI/SCTE 25-3 v1.0 to standard ANSI/SCTE 25-3 v1.1 (2005)
have been taken into account in this second edition.
• Clause 7 is based on standard ANSI/SCTE 110 (2005).
• Addition of informative Annex A concerning hybrid management sub-layer.

– 6 – 60728-7-3 © IEC:2009(E)
The text of this standard is based on the following documents:
CDV Report on voting
100/1464/CDV 100/1599/RVC
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
A list of all parts of the IEC 60728 series, under the general title Cable networks for television
signals, sound signals and interactive services, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until
the maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in
the data related to the specific publication. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates that it contains
colours which are considered to be useful for the correct understanding of its contents. Users
should therefore print this document using a colour printer.

60728-7-3 © IEC:2009(E) – 7 –
INTRODUCTION
Standards of the IEC 60728 series deal with cable networks including equipment and associ-
ated methods of measurement for headend reception, processing and distribution of television
signals, sound signals and their associated data signals and for processing, interfacing and
transmitting all kinds of signals for interactive services using all applicable transmission me-
dia.
This includes
• CATV -networks;
• MATV-networks and SMATV-networks;
• individual receiving networks;
and all kinds of equipment, systems and installations installed in such networks.
The extent of this standardization work is from the antennas and/or special signal source in-
puts to the head-end or other interface points to the network up to the terminal input.
The standardization of any user terminals (i.e. tuners, receivers, decoders, multimedia termi-
nals, etc.) as well as of any coaxial, balanced and optical cables and accessories thereof is
excluded.
The following differences exist in some countries:
The Japanese de facto standard (NCTEA S-006) concerning requirements for the HFC out-
side plant management, which was published in 1995, has already been available in Japan.
The purpose of this standard is to support the design and implementation of interoperable
management systems for HFC cable networks used in Japan.

___________
This word encompasses the HFC networks used nowadays to provide telecommunications services, voice,

data, audio and video both broadcast and narrowcast.

– 8 – 60728-7-3 © IEC:2009(E)
CABLE NETWORKS FOR TELEVISION SIGNALS,
SOUND SIGNALS AND INTERACTIVE SERVICES –

Part 7-3: Hybrid fibre coax outside plant status monitoring –
Power supply to transponder interface bus (PSTIB)

1 Scope
This part of IEC 60728 specifies requirements for the Hybrid Fibre Coax (HFC) Outside Plant
(OSP) Power Supplies (PS). This standard is part of a series developed to support the design
and implementation of interoperable management systems for evolving HFC cable networks.
The purpose of the standards is to support the design and implementation of interoperable
management systems for evolving HFC cable networks. The Power Supply to Transponder In-
terface Bus (PSTIB) specification describes the physical (PHY) interface and related messag-
ing and protocols implemented at the Data Link Layer (DLL), layers 1 and 2 respectively in the
7-layer ISO-OSI reference model, that support communications between compliant trans-
ponders and the managed OSP power supplies and other related power equipment to which
they interface.
This standard describes the PSTIB PHY and DLL layer requirements and protocols that shall
be implemented to support reliable communications between all type 2 and type 3 compliant
OSP transponders on the HFC plant and managed OSP power supplies and related hardware.
Any exceptions to compliance with this standard will be specifically noted as necessary.
Transponder type classifications referenced within the HMS series of standards are defined in
Table 1.
Table 1 – Transponder type classifications
Type Description Application
• This transponder interfaces with legacy network
equipment through proprietary means.
Refers to legacy transponder equip-
Type 0
ment which is incapable of supporting
• This transponder could be managed through the
the specifications
same management applications as the other types
through proxies or other means at the head-end.
• This transponder interfaces with legacy network
equipment through proprietary means.
Refers to stand-alone transponder
equipment (legacy or new), which can
• Type 1 is a standards-compliant transponder (either
Type 1
be upgraded to support the specifica-
manufactured to the standard or upgraded) that con-
tions
nects to legacy network equipment via a proprietary
interface.
• This transponder interfaces with network equipment
designed to support the electrical and physical
specifications defined in the standards.
Refers to a stand-alone, compliant
Type 2
transponder
• It can be factory or field-installed.
• Its RF connection is independent of the monitored
NE.
• This transponder interfaces with network equipment
designed to support the electrical specifications de-
fined in the standards.
• It may or may not support the physical specifications
Refers to a stand-alone or embedded,
Type 3
defined in the standards.
compliant transponder
• It can be factory-installed. It may or may not be
field-installed.
• Its RF connection is through the monitored NE.

60728-7-3 © IEC:2009(E) – 9 –
A list of documents in the HMS specifications family is provided in informative Annex A.
2 Normative references
The following referenced documents are indispensable for the application of this document.
For dated references, only the edition cited applies. For undated references, the latest edition
of the referenced document (including any amendments) applies.
IEC 60603-7, Connectors for electronic equipment – Part 7: Detail specification for 8-way, un-
shielded, free and fixed connectors
3 Terms, definitions and abbreviations
3.1 Terms and definitions
For the purposes of this document, the following definitions apply.
3.1.1
data link layer
DLL
layer 2 in the Open System Interconnection (OSI) architecture; the layer that provides ser-
vices to transfer data over the physical transmission link between open systems
3.1.2
network element
NE
an active element in the outside plant (OSP) that is capable of receiving commands from a
head-end element (HE) in the head-end and, as necessary, providing status information and
alarms back to the HE
3.1.3
open system interconnection
OSI
framework of International Organization for Standardization (ISO) standards for communica-
tion between multi-vendor systems that organizes the communication process into seven dif-
ferent categories that are placed in a layered sequence based on the relationship to the user.
Each layer uses the layer immediately below it and provides services to the layer above. Lay-
ers 7 through 4 deal with end-to-end communication between the message source and desti-
nation, and layers 3 through 1 deal with network functions
3.1.4
physical layer
PHY
layer 1 in the Open System Interconnection (OSI) architecture; the layer that provides ser-
vices to transmit bits or groups of bits over a transmission link between open systems and
which entails electrical, mechanical and handshaking procedures
3.1.5
transponder
device that interfaces to outside plant (OSP) NEs and relays status and alarm information to
the HE. It can interface with an active NE via an arrangement of parallel analogue, parallel
digital and serial ports
– 10 – 60728-7-3 © IEC:2009(E)
3.2 Abbreviations
CATV Community Antenna Television (network)
DLE Data Link Escape
DLL Data Link Layer
EIA Electronic Industries Alliance
EMS Element Management System
ETX End of Text
Gnd Ground
HE Head-end Element
HFC Hybrid Fibre Coax
HMS Hybrid Management Sub-Layer
ISO International Organization for Standardization
LED Light Emitting Diode
MAC Media Access Control
MATV Master Antenna Television (network)
MIB Management Information Base
NE Network Element
OSI Open System Interconnection
OSP Outside Plant
PHY Physical
PSTIB Power Supply to Transponder Interface Bus
RF Radio Frequency
Rx Receive
SNMP Simple Network Management Protocol
STX Start of Text
Tx Transmit
Tx En Transmit Enable
xpndr Transponder
4 Reference architecture forward and return channel specifications
The reference architecture for the series of specifications is illustrated in Figure 1.

60728-7-3 © IEC:2009(E) – 11 –

Fiber Node
RF
RF Optical RF
Laser
RECEIVER
TRANSMITTER Receiver
Splitter
RF Amplifier C hain
Headend
Status
Status
Monitoring
*
Monitoring
Diplexer
Device
Equipment
Optical RF
RF RF
Laser
Receiver Combiner
RECEIVER
TRANSMITTER
B C A
* The diplexer filter may be included as part of the network element to which the
transponder interfaces, or it may be added separately by the network operator.
IEC  2293/03
Figure 1 – Reference architecture diagram
All quantities relating to forward channel transmission or reverse channel reception are meas-
ured at point A in Figure 1. All quantities relating to forward channel reception or reverse
channel transmission are measured at point B for two-port devices and point C for single-port
devices as shown in Figure 1.
5 Power supply to transponder interface bus specification overview
5.1 General
PSTIB specification defines a status monitoring topology intended to replace existing analog,
discrete status monitoring interfaces used today for monitoring power supplies and other
power-related equipment deployed in HFC networks. In this topology, the transponder is sim-
plified by moving all measurements and sensors to the monitored equipment, i.e. power sup-
ply or other power equipment. The transponder interfaces to the monitored equipment through
a single multi-conductor cable. Transponder power is also provided through this interface. The
power supply or other monitored power equipment assumes responsibility for measuring bat-
tery parameters, voltages, and other data associated with the equipment installation. Status
and commands are passed between transponder and monitored equipment via a serial data
interface bus.
The data protocol and command set are simple enough to be implemented in a simple micro-
controller. The communication protocol is open and expandable so that as new requirements
are defined they can be easily added to new revisions of this specification.
5.2 Interface compliance
Transponder and power supply vendors meeting the mechanical and electrical interface re-
quirements at the PHY layer and the packet and protocol message formats at the DLL layer
that are defined within this specification are said to be interface compliant. A
Get_Configuration command (see 8.4.3) enables the transponder to determine compliance
with a particular revision of this standard for power supplies or other power equipment. Sup-
port for this capability is critical as the PSTIB specification is updated over time and power
supply equipment supporting different revisions of this specification co-exists within the same
network.
5.3 Implementation compliance
Not all vendors will support the complete data set defined throughout this standard. The
Get_Configuration response (see 8.4.3) provides the transponder or EMS with the specific
status data that is and is not supported for each installation.

– 12 – 60728-7-3 © IEC:2009(E)
5.4 Revision control
The command and response data in this standard are synchronized with associated HMS
SNMP MIBs (see Table A.1) that are used to represent this data in management systems. To
maintain synchronization, a revision control mechanism shall exist. Therefore, any time this
standard is revised so that new data items are added to any command or response, those
data items shall be appended to the END of an existing command or response definition. New
command and response sequences may also be created as needed. No revision shall change
the location, definition or function of a previously defined datum.
6 Power supply to transponder interface bus – Physical layer specification
6.1 Interface requirements
6.1.1 Connector type
The physical connector to support serial communications over the PSTIB between compliant
transponders and managed OSP power supply hardware shall implement the following:
a) RJ-45 connector, eight-wire conductor, according to IEC 60603-7;
b) appropriate metallic plating for outdoor usage;
c) operating temperature: –40 °C to +70 °C;
d) dual connectors wired in parallel shall be included on the monitored equipment to support
daisy-chaining multiple monitored devices from a single compliant transponder.
6.1.2 Communications interface
The communications interface shall support the EIA RS-485 [1].
6.1.3 Connector signals
Connector pins shall support signalling as described in Table 2.
Table 2 – RJ-45 Connector pin assignment
Connector
Signal
pin number
1, 8 Ground
2, 7
+24 V ± 15 % at 200 mA
DC
3, 6 RS-485 (+)
4, 5 RS-485 (–)
6.1.4 Transponder power
Powering of transponders from PSTIB interface compliant power supplies shall support the
following attributes:
a) the transponder is powered only from the power supply. The transponder shall not connect
directly to the system batteries;
b) the power supply shall implement appropriate isolation and system grounding so that the
communication interface and transponder power remains functional under the operating
conditions defined herein;
c) the transponder shall be bonded to chassis ground directly and/or through the system co-
axial cable sheath;
60728-7-3 © IEC:2009(E) – 13 –
d) optionally, transponder power may be bonded to chassis ground at the power supply inter-
face. The power supply vendor shall determine this;
e) the power supply shall implement appropriate over-current and short-circuit protection of
transponder power so that the communication interface and transponder power remain
functional under the operating conditions defined herein;
f) up to eight (8) power supplies may be connected in parallel using the RS-485 interface.
6.1.5 Line balance
6.1.5.1 Monitored equipment
Line balance for monitored equipment shall be implemented as follows:
a) RS-485 (+) to a DC voltage of +5 V through a resistor (jumper/switch removable);
b) RS-485 (–) to ground through a resistor (jumper/switch removable);
c) RS-485 (+) tied to RS-485 (–) through a resistor (jumper/switch removable);
d) monitored equipment shall include jumpers to select or bypass resistors to an open state.
Jumper or switch-selectable terminating resistors enable on-site configuration of individual
installations. Transponders shall include line balance resistors only. Refer to Figure 2.
6.1.5.2 Transponder
Line balance for transponders shall be implemented as follows:
– RS-485 (+) tied to RS-485 (–) through a required resistor.
NOTE Values for each resistor and the decision to include or exclude specific bias resistors as a default should
be determined by individual vendors.
6.1.6 Cable length
A maximum cable length of 1 219,2 m (4 000 ft) (for 100 kbit/s) properly terminated wire seg-
ment.
6.1.7 Data encoding
Non-return to zero (NRZ), asynchronous, 1 start bit, 8 data bits (ordering: bit 1,2 … 8), 1 stop
bit. All integers are transmitted most significant byte first. Any exceptions to this rule will be
specifically noted in this standard as necessary.
6.1.8 Bit rate
The bit rate supported shall be 9 600 Bd.
6.1.9 Duplex
This interface shall support half duplex operation. Multi-drop characteristics of RS-485 enable
up to 32 drops per segment without signal repeaters.
6.1.10 Method of communications
All communication is transponder-initiated. One monitored device response per query.
6.1.11 Indicators
A LED or other visual device installed at the monitored equipment shall indicate communica-
tion has been established with a transponder over the PSTIB interface.

– 14 – 60728-7-3 © IEC:2009(E)
6.2 Interface diagram
The diagram in Figure 2 illustrates a sample RS-485 interface implementation to support
PSTIB communications. This diagram should not be interpreted as a design requirement. It is
only included to help clarify line bias and termination resistor placement. Table 3 describes
the various signals that have been referenced in this diagram.

MONITORED
TRANSPONDER
EQUIPMENT
+5 +Vxpndr +Vxpndr +5xpndr
+5
750 8
* Option
V c c
J1 J2
V c c
Rx
1 1
R
Rx
R 2 2
3 3
120 2
4 4
2 Tx En
5 5 Required
Tx En
* Option
6 6
7 7
Tx
7 4
8 8 D
Tx 4
D
G n d
G n d 750
5 * Option
IEC  2304/03
Figure 2 – Sample PSTIB RS-485 interface
Table 3 – Sample PSTIB RS-485 interface – Reference signals
Signal notation Description
(see Figure 2)
+5 Monitored equipment voltage
+Vxpndr Voltage supplied from the monitored equipment to the transponder as defined per this
specification
+5xpndr Transponder operating voltage derived at the transponder from +Vxpndr
*Option Indicates resistors that can be included or removed from circuit via user configurable
jumper or switch
Required Indicates resistor is required per this specification
J1, J2 The RJ-45 connectors according to IEC 60603-7 used to interface transponders to
monitored equipment. Pin numbers show currently defined interface signals per this
specification
Rx, Tx, Tx En Transmit, Receive and Transmit Enable. Illustrates possible connections to an RS-485
interface IC.
GROUND The transponder should be chassis grounded. The monitored equipment may be tied to
chassis ground directly, i.e. at the monitored equipment status interface, or through the
interface ground (J1 pins 1,8). This should be at the discretion of the monitored equip-
ment vendor. The monitored equipment and status interface should function correctly
with whatever grounding method is selected.

60728-7-3 © IEC:2009(E) – 15 –
7 Alternative power supply to transponder interface bus – Physical layer
specification
7.1 Introduction to alternative
Some applications have been identified that may have under certain conditions a powering
requirement which exceeds those defined in Clause 6. Therefore this physical layer specifica-
tion of an alternative power supply to transponder interface bus forms a supplement to the
specifications in Clause 6 and will coexist with them.
7.2 Interface requirements
7.2.1 Connector type
The physical connector to support serial communications over the PSTIB between compliant
transponders and managed OSP power supply hardware shall implement the following:
a) RJ-45 connector, eight-wire conductor, according to IEC 60603-7;
b) appropriate metallic plating for outdoor usage;
c) operating temperature: –40 °C to +70 °C;
d) dual connectors wired in parallel shall be included on the monitored equipment to support
daisy-chaining multiple monitored devices from a single compliant transponder.
7.2.2 Communications interface
The communications interface shall support the EIA RS-485 [1].
7.2.3 Connector signals
Connector pins shall support signalling as described in Table 4.
Table 4 – RJ-45 Connector pin assignment
Connector Signal
pin number
1, 8 Ground
2, 7
+24 V ± 15 % at 4,8 W
DC
3, 6 RS-485 (+)
4, 5 RS-485 (–)
7.2.4 Transponder power
The following requirements apply to transponder power.
a) The power supply shall implement appropriate isolation and system grounding such that
the communication interface and transponder power remains functional under the operat-
ing conditions defined herein.
b) The transponder shall be bonded to chassis ground directly and/or through the system co-
axial cable sheath.
c) Optionally, transponder power may be bonded to chassis ground at the power supply inter-
face. The power supply vendor shall determine this.
d) The power supply shall implement appropriate over-current and short-circuit protection of
transponder power such that the communication interface and transponder power remain
functional under the operating conditions defined herein.
e) Up to eight (8) power supplies may be connected in parallel using the RS-485 interface.

– 16 – 60728-7-3 © IEC:2009(E)
f) Under the operating requirements defined herein, the power supply shall be able to supply
4,8 W of continuous power to the PSTIB.
g) Under the operating requirements defined herein, the Transponder shall draw no more
than 4,8 W of power from the PSTIB.
h) During start-up, while the power supply is coming up to the minimum voltage requirement,
the transponder shall limit inrush current to no more than 250 mA and power draw to no
more than 4,8 W.
i) During start-up the power supply shall achieve the minimum voltage requirement within
1 s.
7.2.5 Line balance
7.2.5.1 Monitored equipment
Line balance for monitored equipment shall be implemented as follows:
a) RS-485 (+) to a DC voltage of +5 V through a resistor (jumper/switch removable);
b) RS-485 (–) to ground through a resistor (jumper/switch removable);
c) RS-485 (+) tied to RS-485 (–) through a resistor (jumper/switch removable);
d) monitored equipment shall include jumpers to select or bypass resistors to an open state.
Jumper or switch-selectable terminating resistors enable on-site configuration of individual
installations. Transponders shall include line balance resistors only. Refer to Figure 3.
7.2.5.2 Transponder
Line balance for transponders shall be implemented as follows:
– RS-485 (+) tied to RS-485 (–) through a required resistor.
NOTE Values for each resistor and the decision to include or exclude specific bias resistors as a default should
be determined by individual vendors.
7.2.6 Cable length
Maximum cable length of 1 219,2 m (4 000 ft) (for 100 kbit/s) for a properly terminated wire
segment.
7.2.7 Data encoding
Non-return to zero (NRZ), asynchronous, 1 start bit, 8 data bits (ordering: bit 1,2 … 8), 1 stop
bit. All integers are transmitted, the most significant byte first. Any exceptions to this rule will
be specifically noted in this standard as necessary.
7.2.8 Bit rate
The bit rate supported shall be 9 600 Bd.
7.2.9 Duplex
This interface shall support a half duplex operation. Multi-drop characteristics of RS-485 en-
able up to 32 drops per segment without signal repeaters.
7.2.10 Method of communication
All communication is transponder-initiated, one monitored device response per query.

60728-7-3 © IEC:2009(E) – 17 –
7.2.11 Indicators
A LED or other visual device installed at the monitored equipment shall indicate communica-
tion has been established with a transponder over the PSTIB interface.
7.3 Interface diagram
The diagram in Figure 3 illustrates a sample RS-485 interface implementation to support
PSTIB communications. This diagram should not be interpreted as a design requirement. It is
only included to help clarify line bias and termination resistor placement. Table 5 describes
the various signals that have been referenced in this diagram.

MONITORED
TRANSPONDER
EQUIPMENT
+Vxpndr +Vxpndr +5xpndr
+5
+5
* Option
V c c
J1 J2
V c c
Rx
1 1
R
Rx
R 2 2
3 3
120 2
4 4
120 Tx En
2 3
Required
5 5
Tx En
* Option
6 6
7 7
Tx
7 4
8 8 D
Tx
D
G n d
G n d
* Option
IEC  2304/03
Figure 3 – Sample PSTIB RS-485 interface
Table 5 – Sample PSTIB RS-485 interface – Reference signals
Signal notation
Description
(see Figure 3)
+5 Monitored equipment voltage
+Vxpndr Voltage supplied from the monitored equipment to the transponder as defined per this
specification
+5xpndr Transponder operating voltage derived at the transponder from +Vxpndr
*Option Indicates resistors that can be included or removed from circuit via user configurable
jumper or switch
Required Indicates resistor is required per this specification
J1, J2 The RJ-45 connectors according to IEC 60603-7 used to interface transponders to
monitored equipment. Pin numbers show currently defined interface signals per this
specification
Rx, Tx, Tx En Transmit, Receive and Transmit Enable. Illustrates possible connections to an RS-485
interface IC.
GROUND The transponder should be chassis grounded. The monitored equipment may be tied to
chassis ground directly, that is at the monitored equipment status interface, or through
the interface ground (J1 pins 1,8). This should be at the discretion of the monitored
equipment vendor. The monitored equipment and status interface should function cor-
rectly with whatever grounding method is selected.

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8 Power supply to transponder interface bus – Data link layer specification
8.1 DLL packet structure
8.1.1 General
DLL packets consist of the following: start field, destination address field, source address
field, identification field, a variable-length datagram field, end field and two-byte ch
...