Contemporary Controls ARCNET PCX20 Installation Manual

PCX20
®
ARCNET Network Interface Modules
INSTALLATION GUIDE
INTRODUCTION
The PCX20 series of ARCNET network interface modules (NIMs) links
PC/XT/AT (ISA) compatible computers with the ARCNET local area
network (LAN).
ARCNET is classified as a token-bus LAN operating at a nominal 2.5 Mbps
while supporting 255 nodes. Interfacing ARCNET to a host computer
usually requires a NIM which plugs into the host computer's bus.
The PCX20 incorporates the newer COM20020 ARCNET controller chip
with enhanced features over the earlier generation ARCNET chips. New
performance and integration enhancements include command chaining
operation and an internal 2K x 8 RAM buffer. There is no requirement for
wait-state arbitration.
Each PCX20 module has two LEDs on the board. The green LED indicates
that the module is receiving data on the network and the yellow LED
indicates host bus access to the module. The PCX20 also has a piano-style
DIP switch so that node addresses can be easily reassigned without
removing the module.
There are several versions of the PCX20 ARCNET NIM. The PCX20-CXS
supports coaxial star configurations requiring external active or passive
hubs. The PCX20-CXB supports coaxial bus configuration usually requiring
no hubs. Other versions include the PCX20-FOG which supports fiber optic
cable with either ST or SMA connectors. The PCX20-TPB supports twisted-
pair bus cabling using RJ-11 and screw terminal connectors. There are
various versions that support EIA-485 communication each using RJ-11 and
screw terminal connectors.
On some models, operation up to 5.0 Mbps is possible. These models are
identified with a /5 designation.