Measurement Computing Extender 488HS Rev.2.0 - Manual (Page 29)

Section 4 Service Information
4.1
Service Information
4.1 Factory Service
IOtech maintains a factory service center in Cleveland, Ohio. If problems are
encountered in using the Extender488/HS Bus Extender, you should first telephone the
factory. Many problems can be resolved by discussing the problem with our applications
department. If the problem cannot be solved by this method, you will be instructed as to
the proper return procedure.
4.2 Theory of Operation
The Extender488/HS Bus Extender is controlled by two programmable array logic
integrated circuits. Each Extender488/HS monitors the control and handshake lines on
each bus and the internal logic determines the correct direction for all data transceivers.
Communication between each Extender488/HS is accomplished using RS-422
transceivers. These transceivers as well as the IEEE 488 transceivers are controlled by the
internal logic.
4.3 Extender488/HS Cable Construction
The following information is provided for users that want to make their own
interconnecting cable for Extender488/HS. Shielded twisted pair cable must be used and
the pairs must be connected as shown in the cable wiring diagram.
Shielded Male Connector: AMP 554953-2 (or equivalent)
Cover: AMP 554946-2 (or equivalent)
Cable: 24 AWG., 50 conductor
shielded cable (25 twisted
pairs). Nominal capacitance
between conductors for each
pair must be less than 13 pF per
foot.