Siemens TC12 Installation, Commissioning And Maintenance Handbook page 16

TC12 Installation, Commissioning & Maintenance Handbook
Instation
The Instation comprises of one or more Traffic control computers (TCC) and one
or more Instation Transmission Units (ITUs). The ITU cabinets are 32U high with
grey panelling and a smoked glass front door.
Traffic Control Computer
The TCC is a system containing a minimum of one machine and one PC per ITU
cabinet. The UTC TCC system communicates with the PC(s) via an Ethernet link.
More than one UTC TCC will be used should the number of modems required
demand it.
Instation Unit
The ITU cabinet is fitted with a PC at the top, and space for up to four racks below
it. These racks will be either ITU or Digital output racks, but the bottom space can
be used for an OTU if required. There is also a mains distribution system with
spare sockets, and facility for mounting a PSTN modem that would connect to the
UTC TCC to allow remote interrogation.
System Fault Indication Panel
The System Fault Indication Panel (SIP) is positioned in front of the PC and
houses LEDs to warn of various failures. There is also an audible alarm on the SIP
that can be cancelled by a switch next to it or disabled by a switch on the PSU
board.
ITU Rack
A full ITU rack contains three types of board; four modem boards, four transformer
boards and a power supply board.
The modem board has four modem chips that communicate with the PC via a V.24
link. These modems are connected to the OTU via the telephone lines in either
radial, multidrop or multipoint format. There is also a pair of test jacks on the
modem board to allow connection to the Instation test set to monitor
communications data and measure signal levels.
The transformer board is used, when the system is in radial configuration, to split
each modem to up to eight telephone lines. This gives a maximum of 128
telephone lines per rack.
The PSU board supplies power to the ITU rack. It also interfaces between the PC
and the SIP and allows connection to a TC8 ITU rack. This facility would be used
should a TC8 system be expanded with TC12.
666/HE/43100/000 Page 6 Issue 10