ABB S900 Manual page 10

I/O System S900
Communication Interface for PROFIBUS DP, CI920
(Eex-e) to ensure explosion protection. Appropriate ready-made S900 field
housings are available for this purpose. The I/O System S900 is powered via
special terminals with increased safety located on the mounting termination
unit. The power supply units, the communication interfaces, and the I/O
modules are plugged into the mounting termination unit and locked
automatically. The power supply modules have a built-in shut-off mechanism
with automatic locking and can be plugged/removed under power in zone 1,
although the supply in the primary circuit which is not intrinsically safe is still
active in this case. As a result, the I/O System S900 does not require an
explosion-proof or pressurized housing and, therefore, is easy to handle.
The mounting termination unit and the power supply unit(s) ensure
intrinsically safe power supply of the communication interfaces and up to 16
I/O modules. The mounting termination unit provides all internal connections.
Thus, only the peripheral units need to be connected by the user. Also, hot
swapping of the communication interfaces and I/O modules is possible, i.e.
these units can be connected or removed during operation. This ensures easy
replaceability of all active components, and a high degree of flexibility and
user-friendliness.
Field instruments complying with protection class EEx ia IIC can be
connected to the I/O modules. At present, up to 16 I/O modules can be run on
the same mounting termination unit. Each I/O modules is designed for
connecting 4 or 8 field instruments, depending on the respective model. The
I/O modules and the underlying field instrument level are powered via the
mounting termination unit. All intrinsically safe modules are self-feeding and
short-circuit proof. No separate routing level with additional power supply
and individual fusing is required.
HART communication in the field with all analog S900 I/O modules is
possible via a PC or hand-held terminal. In addition, the special HART
variants allow for a consistent HART communication up to the open control
system (OCS). Cyclic transmission of all secondary HART variables, HART
diagnostics, and (non-cyclic) configuration of all HART devices are possible.
The S900 I/O modules are slot-addressed and, therefore, do not require any
settings on the modules themselves. The PROFIBUS address is either set via
three coding switches, or is assigned via the system.
The S900 communication interface, the I/O modules, and the connected
HART devices are configured and parameterized via a fieldbus network. No
additional network is required for this. The communication interface and the
10 3BDD010422R0101