Hatteland Display 20 inch - HM 20T07 MIL-H - Manual (Page 48)

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IND100084-7
HATTELAND® SCOM A1 & C1 Control Interface
This document defines the electrical signals, connectorization, serial data format, and communication protocol of the
A1 and C1 version Serial Communication Control Interface. Difference between A1 and C1 is that C1 version provides
filtered Dsub contacts for military applications. The purpose of this interface is to provide means for a computer
application to control the LCD backlight and menu of one or more units. By units we refer to either displays or panel
computers.
Interface configuration
The serial interface can have different configurations, selected by three switches.
The configurations are defined as follows:
RS 232 One computer controls one unit, no individual address
RS 485 Half duplex One computer controls max 16 units, each with individual address.
Full duplex
Brightness Control Operation
The backlight brightness at the unit can be controlled in two modes. A serial interface is used to command the level of
backlight brightness and to select mode.
1) Using the local manual brightness control, an operator is only able to adjust brightness to levels lower than the set
maximum, including dimming the backlight to extinction.
2) Brightness is independent of local manual brightness control, set by remote control only.
Electrical Interface
Electrical signals shall conform to RS-485, RS-422 or RS-232. Only Receive Data, Transmit Data, and Signal Ground
are used. The same conditions apply for both RS-422 and RS-485, and will just be referred to as RS-485 further on
in this document. Hardware handshake is only supported by loopback handshake for RS-232.
Dual 232 and 485 Electrical Interface
Of the two types of electrical interfaces 232 and 485, only one type shall be connected in a given installation, not
both. Both receive and transmit capabilities shall be supported. 485 interface supports both half and full duplex.
Electrical interface and duplex are selected with switches at the back of the display
Cable
A cable with an overall shield terminated at the back shell should be used.
Communication Interface
Serial Communication (SCOM) Interface