EverFocus EKR-KB1 operating instructions RS485 and system types, Setup Description Example

3 Communi cation lines and connections

3.1 Video and telemetry lines

The EKR-KB1 keyboard can be used to control a wide range of products, for both video control (video matrixes and multiplexers) and telemetry control (receivers and domes). It is therefore necessary to define the system structure at the keyboard level to achieve efficient communication between the connected devices.

“Video line” means the communication channel intended to control the video devices; “telemetry lines” means the two channels available for telemetry control.

We advise starting with the setup of the single “video line” and after that passing to the setup of the “telemetry lines”.

3.2 RS485 and system types

The RS485 communication channels are 2-wire lines whose maximum length from end to end is 1200m.

The termination of the RS483 lines prevents signal reflection along the cable and should be inserted in each of the devices that forms the end of a connection.

Systems can be of different types, therefore the way of terminating the lines will also be different. In the diagrams shown below, the devices requiring termination are indicated by the # symbol.

Setup	Description	Example
Star	/ For each connection between two
Single lines	devices there should be a separate
	communication line, with a maximum
	length of 1200m.
	All devices should be terminated, since
	each device is connected to an end of
	the line
Backbone	A single line is used, and the
	transmitters can be placed in any
	position along it. The two ends of the
	line (keyboard K and receiver R3 in the
	example) are terminated; the other
	devices (R1 and R2) are not
	terminated. The maximum length of the
	line is 1200m.
	The specifications for the RS485
	standard allow at least 32 devices to be
	connected along the same line.
Line with stub	A certain number of stubs can be
	shunted in parallel to the normal RS485
	line, for connection to other devices.
	Since the stubs are not at the ends of
	the line, they should not be terminated
	and they should be very short in length
	(of the order of a couple of metres).

The specifications for the RS485 standard allow at least 32 devices to be connected along the same line.

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