
TPU2000/2000R Modbus/Modbus Plus Automation Guide
2
The products differentiate themselves as listed in Table 1-1. Table 1-1 lists the available protocols within the
relays. Standard Ten Byte is an ABB protocol which is within the TPU2000 and TPU2000R protective relays.
Standard Ten Byte is an asynchronous byte oriented protocol. The programming software (ECP [DOS External
Communication Program] and WINECP [Windows External Communication Program]) allows configuration of the
relay through a port on the units. Standard Ten Byte is available through an RS232 or RS485 port on the TPU.
INCOM is an ABB protocol, which is a derivative of Standard Ten Byte. It is a modulated synchronous bit stream
using the same commands as in the Standard Ten Byte protocol. INCOM is available as an option for the
TPU2000 and TPU2000R relays as indicated within Table 1-1. Its physical interface is proprietary in that the TPU
node expects a modulated signal.
Serial
Modbus
is an industrial de-facto standard protocol, which has been widely embraced by the utility industry.
Modbus has two emulation’s, RTU, which is a synchronous protocol and ASCII which is an asynchronous
protocol. Modbus uses only one command set, but two emulation’s. Modbus strengths are that it uses a
standard RS 232 or RS 485 interface to interconnect nodes on a network.
TCP/IP Modbus
is an evolution of Serial Modbus in that it uses Ethernet as the mechanism to transfer the
Modbus Serial packets across an Ethernet LAN. It is gaining in popularity in that several protocols and network
transmissions may peaceably coexist on a single network cable. Network Modbus (or TCP/IP Modbus) has its
own protocol conventions and is not merely initiation of an Ethernet TELNET session over the Local Area Network
(LAN).
Modbus Plus is a hybrid protocol refinement of Modbus. Modbus Plus has a proprietary physical interface which
is available to device manufacturers through a connectivity program with Groupe Schneider. The interface offers
greater speed and communication features than Modbus.
DNP 3.0 is a protocol, which has its roots deep in the utility industry. It is an asynchronous protocol that allows
connectivity through a standard RS232 or RS485 port. It includes such defined capabilities as file transfer, and
timestamping as part of the protocol, which makes it desirable for a utility implementation.
Table 1-1. Protocol Capabilities Listed by Product Type
PRODUCT
PROTOCOL
NOTES
TPU2000
Standard Ten Byte
Addressable Front Com, Com 1 and Aux Com
INCOM
2 Wire (and Shield) Current Injection Physical Interface
Modbus
RS232 or RS485
DNP 3.0
RS232 or RS485
TPU2000R
Standard Ten Byte
RS232 or RS485
INCOM
2 Wire (and Shield) Current Injection Physical Interface
Serial Modbus
RS232 or RS485
TCP/IP Modbus
Ethernet or Fiber Optic Connection
Modbus Plus
Proprietary Current Injection Physical Interface
DNP 3.0
RS232 or RS485
Within this document, only
Modbus,
and
Modbus Plus
protocols shall be covered in depth. Standard 10 Byte,
INCOM and DNP 3.0 shall be explained superficially. If one would need to reference the specific details of
Standard Ten Byte or INCOM protocols, please reference the engineering specifications concerning these topics
in Appendix A of this document.