PCX20 Serie

PCX20 Series — ARCNET® Adapters for PC/XT/AT Bus Computers

The PCX20 Series of Network Interface Modules (NIMs) offers dependable ARCNET connectivity for XT/AT compatible computers.

This product is designed with the COM20020 ARCNET controller chip. Features include command chaining, sequential access to internal RAM, duplicate node ID detection, and variable data rates up to 5 Mbps. There is no requirement for wait-state arbitration.

Each PCX20 module has two LEDs on the board for monitoring network operation and bus access to the module. It also has an external DIP switch so that node addresses can be easily reassigned without removing the module or opening the computer case.There are several models in the PCX20 Series. The PCX20-CXS supports coaxial star configurations requiring external hubs if other than point-to-point communication is needed. The PCX20-CXB accommodates a multidrop or coaxial bus configuration, typically without any hubs. Other versions include the PCX20-FOG-ST for fibre optic cable with ST connectors. The PCX20-TPB supports multidrop twisted-pair cabling using RJ-11 and screw terminal connectors. Two units provide DC-coupled EIA-485 operation: the PCX20-485 allows backplane mode to be controlled by the user’s software, while the PCX20-485D forces backplane mode via hardware for those users having legacy software that is incapable of invoking backplane control. The PCX20-485X offers transformer-coupled EIA-485 operation with the backplane mode forced through hardware.

Details zur PCX20 Serie

• No requirement for wait-state arbitration
• Enhanced software capabilities over earlier generation ARCNET controllers
• Supports coaxial, fibre optic, and twisted-pair cabling including EIA-485
• Node address switch selects one of 255 possible station addresses
• Variable data rates up to 5 Mbps
• Suitable with all Contemporary Controls
• MOD HUB and AI Series active hubs
• CMOS design for low-power consumption
• CE Mark
• RoHS
• Utilises COM20020 ARCNET controller
• Interfaces ARCNET with XT/AT (ISA) bus computers
• I/O-only mapping reduces bus contention problems

Analoge Signale

Coaxial Bus Topology (PCX20-CXB)

Cards with –CXB transceivers accept RG-62/u cable via BNC Tee connectors. Each node is a high-impedance in both powered and unpowered states. BNC-style 93Ω terminators must be applied to both ends of a bus segment. The maximum segment length is 305 metres and up to 8 devices can share the segment.

Coaxial Star Topology (PCX20-CXS)

In a –CXS coaxial star system, devices connect in a point-to-point fashion with RG-62/u coaxial cabling not exceeding 610 metres. If more than two cards share the cabling, a hub is needed. A -CXS card provides the 93Ω of termination internally.

Twisted-Pair Bus Topology (PCX20-TPB)

A -TPBdipulse transceiver supports up to 8 devices and 122 metres of shielded or unshielded twisted-pair. Apply terminators at each end of the bus.

EIA-485 (Digital) Signale

DC-coupled EIA-485 (PCX20-485 or PCX20-485D)

EIA-485 backplane mode is invoked in the -485 card via user software and in the -485D card via the card’s own hardware. Either card supports twisted-pair up to 274 metres in length and up to 17 nodes. Use proper cable and maintain wiring phase integrity among all nodes. Use 120Ω termination and proper bias at each end of the bus.

AC-coupled EIA-485 (PCX20-485X)

Backplane mode is invoked by the hardware in the -485X card which supports up to 13 devices and a segment length of 213 metres. Apply 120Ω termination at each end of the bus.

Multimode Fibre Optic Signale

ST-connected Duplex Fibre (PCX20-FOG-ST)

Fibre models use the ST style connector to support duplex cable of 50, 62.5 or 100 micron diameter.