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-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.
