Features include ...

Two RS232/4xx/20mA ports (port type can be mixed but must be specified when ordering)
7-35V DC powered
Addressable Adapter mode: multidrops non-addressable RS232/422/20mA devices
Three-way isolated (Port 1, Port 2 and power input are mutually isolated)
Automatic Driver Enable on RS485
Data flow indicator LEDs
30-115200 baud, low-emission drivers
High quality removable screw terminals
ANSI C user-programmable model (KD485-PROG)
MODBUS RTU SLAVE library available for building custom protocol converters

KD 485-STD	Software Utilities Disk (422k)
KD 485-ADE	KD 485-PROG

Overview of the KD485

The KD485 is a multi-purpose isolated RS232/422/485/20mA interface converter with intelligent data processing options.

Three standard product versions cover most industrial interface and protocol conversion applications.

Another common requirement is multi-drop connection of non-addressable RS232/422/20mA devices, to enable them to be conveniently polled from a single RS422/485 Master device. The KD485-ADE can act as an "addressable adapter" for each RS232 device.

Many projects involve the interconnection of equipment which is mutually incompatible. The KD485-PROG can be programmed - in ANSI C - to convert virtually any industrial automation protocol into any other. A MODBUS RTU comms library is available for rapid MODBUS RTU SLAVE protocol converter development, enabling a non-MODBUS device to appear as a MODBUS RTU SLAVE device.

Standard Versions

The KD485 is available in three stock versions which share the following common features:

	DIN-rail enclosure with removable screw terminals; fits 35mm symmetric rails
	29mm width on DIN rail
	DC power input in the range +7V to +35V; uses a high efficiency switching power supply
	Two serial ports: port 1 and port 2; isolated from each other and from the power supply
	Port 1 is RS232; port 2 is RS422/485 as standard
	Either port can be factory-fitted as RS232, RS422/485 or 20mA Loop
	Controlled slew rate drivers on RS422/485 ports - no terminators needed for cables shorter than 300m
	Internal pull-up and pull-down resistors on RS422/485 ports ensure that RS485 bus floats to a valid state when not driven.

KD485-STD

This entry level product has no CPU. It is an interface converter/isolator only and is baud rate and character format independent. Its main application is in isolated conversion between RS232, RS422 and 20mA. It can also drive a 2-wire RS485 bus if the RS232 host provides RTS Control

KD485-ADE

As for the KD485-STD but inserts a CPU (with two serial ports) into the data path. Several standard application programs ("Modes") are provided in a built-in ROM:

	Mode 0: emulates KD485-STD; also offers baud rate and character format conversion, with data buffering and precise edge timing regeneration.
	Mode 1: as above, plus Auto Driver Enable. The Port 2 RS485 driver is automatically controlled according to Port 1 receive data; a similar function can also be enabled on Port 1 to form a bidirectional "ADE" converter.
	Mode 2: RS485 Addressable Adapter. This makes possible to connect non-addressable RS232/422/20mA devices to a 2/4-wire RS485 bus, through which they can be polled by a single Master. Devices which emit data continuously are also supported by the KD485's queues. The RS485 address and an optional lead-in byte are fully configurable.

The KD485-ADE can be configured with any "dumb" terminal, a PC or a hand-held terminal such as a Psion Organiser. A PC-based configuration program, KDCFG.EXE, for Windows 3.x and win9x/NT/2000/XP is included on a diskette - click here for an example config screen.

KD485-PROG

This fully programmable version has all the KD485-ADE features, plus a large EEPROM and a means of uploading user-written programs in to it. Programs can be written in ANSI C, assembler and other languages, and are uploaded to the KD485-PROG with supplied software (DOS or Windows).

	A MODBUS RTU library is available which greatly speeds up the development of MODBUS-to-custom protocol converters.
	Download an Acrobat format KD485 MODBUS Library User Manual (133kb)