Hitachi EC701HP Operation Manual page 12

Section 1 - Introduction (UHF Digital TV Transmitters)
E-Compact - Air Cooling - ATSC - High Power
The Architecture of Control for Hitachi Kokusai Linear Transmitters is composed of subcontrol
blocks characterized by Control / Exciter Drawers and by Power Drawer. This architecture
allows the distribution of control functions.
The main control block represents the Control / Exciter Drawer and the sub-control blocks
represent the Power Drawers and Telesupervision Drawer (Remote Control Drawer).
Each sub-block only reports monitoring information to the main control block, and in some
situations the main control block can also transmit commands to the sub-blocks.
The Information reported to the control block is displayed on the primary display.
The control center of each block and sub-block consists of a microcontroller module of 16-bit
and 32-bit, according to its functionality described below:
a)- Main Control Module:
The main control module receives information from the other modules, processes this information
for displaying on the LCD and sends it to the system telesupervision. The main module is also
responsible for checking abnormal conditions and generate alarms, control of transmitted power
levels and general user interface. The main control module can also send commands to the
sub-blocks in situations where it is necessary to enable specific protections for sub-blocks and
also for the control of information sent and received by the remote supervision system.
b)- Power Drawer's Control Module
The control module sends information to the main module on request. This module has a protection
system fully independent of the main control module. The control module is responsible for
monitoring the power supplies, the readings of forward and reflected power, cooling system,
control of quiescent current according to temperature variation.
Alphanumeric User Interface
The Control/Exciter drawer has a LCD display in it's front panel companied by a keyboard with
six keys, which are: ENTER, ESC, LEFT, RIGHT, UP, DOWN. There is also close to these keys
a set of indicative LEDs for Control/Exciter drawer alarms.
Communication between blocks and sub-blocks
The Control / Exciter Drawer uses a communication system called MODBUS. This is a serial
communication network operated by the Main Control Module in which each node (sub-block)
has its own address. This communication system works with the differential transmission
avoiding interference noise.
Manual Rev. 0.1 - February 2018 1-5