Tpu2000 And Tpu2000R Device Connectivity; Rs232 Interface Connectivity; Port Isolation; Table 3-1. Physical Interface Options - ABB TPU2000 Technical Manual

Section 3 - TPU2000 and TPU2000R Device Connectivity
Communication between devices is only possible through connectivity of the units through a physical media
interface. There are two physical interface types on a TPU2000R and a TPU2000. Table 3-1 lists the
characteristics for each of the port types. Those physical interfaces are:
RS232 (isolated and non-isolated)
RS485 (isolated)

Table 3-1. Physical Interface Options

TPU2000R
COM 0 RS232 Non Isolated
COM 1 RS232 Non Isolated
COM 2 RS232 Non Isolated
COM 3 RS232 Isolated/RS485
Isolated or Modbus Plus
AUX 10 base FL port and
COM ethernet copper
connection OR RS485
(Isolated) and/or INCOM
(2 Winding Unit Only)

RS232 Interface Connectivity

RS232 is perhaps the most utilized and least understood communication interface in use. RS232 is sometimes
misinterpreted to be a protocol; it is in fact a physical interface. A physical interface is the hardware and network
physical media used to propagate a signal between devices. Examples of physical interfaces are RS232 serial
link, printer parallel port, current loop, V. 24, IEEE Bus... Examples of network media are, twisted copper pair,
coaxial cable, free air...
RS232 gained widespread acceptance due to its ability to connect to another RS232 device or modem. A modem
is a device, which takes a communication signal and modulates it into another form. Common forms of modems
include telephone, fiber optic, microwave, and radio frequency.
multiple devices on a communication network or allows extension of communication distances in a network with
two nodes. Physical connection of two devices or more than two devices require differing approaches. Figure 3-1
illustrates a topology using two devices (point to point topology). Figure 3-2 illustrates a multi-drop topology
between many nodes. RS232 was designed to allow two devices to communicate without using intermediate
devices.

Port Isolation

Network installation within a substation requires special considerations. A substation environment is harsh in that
high levels of electromagnetic interference are present.
installations. RS232 is an unbalanced network in that all signals are referenced to a common ground. On
longer cable runs, the potential of the signals at the sending device can be significantly lower than at the receiving
end due to electrical interference and induced ground current. This increases with long runs of cable and use of
unshielded cable. ABB's Substation Automation and Protection Division recommends the length of RS232 cable
be less than 10 feet (3 meters) for an un-isolated port and that the cable be shielded. Internal to a typical device,
the RS232 transceivers are referenced to the electronic components internal ground. Any electrical interference
could be coupled through the chip set and fed back to the device. Typical isolation ratings of a non-isolated port
could be as low as 1 volt. Such a port could allow electrical feedback of noise to the electronics for any signal
interference over 1 volt.
Coms 0 through 2 on TPU/TPU/GPU units are non–isolated. However an RS232 implementation on Com 3 uses
opto-isolation technology which increases electrical isolation from the port to the devices internal circuitry to 2.3
kV. It is highly desirable to utilize this port in connection to devices in longer cable runs and dedicated
communication networks. RS232 isolated ports are limited in connection distance for a maximum of fifty feet.
TPU2000/2000R Modbus/Modbus Plus Automation Guide
TPU2000
RS232 Isolated Front Port Standard 10 Byte
Standard 10 Byte Only
Standard 10 Byte Only
RS232 Isolated TPU2000R – Communication Option Card
( Modbus + NOT Determines Physical Interface
OFFERED)
RS485 (Isolated) RS485 (Isolated) and/or INCOM
and/or INCOM
Additional ground currents are present in such
Notes
Modem connectivity allows attachment of
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