Measurement Computing Extender 488HS Rev.2.0 - Manual (Page 16)

Section 2 Getting Started
2.8
SYMPTOM FAILURE
CONNECT LED off Extender488/HS cable defective
or not properly installed
No LEDs on Power not connected
If the CONNECT LED is not lit on either unit, make sure that the Extender488/HS cable is firmly
seated in the rear panel connector. If the problem is unresolved, refer to the Service Information section of
this manual.
If proper operation is obtained, turn-off the Extender488/HS power switch and connect the other
IEEE devices to each of the Extender488/HS IEEE ports. Apply power to all devices in the system.
Once all IEEE devices have been connected and powered on, the Extender488/HS will allow the
system controller to command up to 13 IEEE devices on its local bus (in addition to itself and the local bus
extender), and up to 14 IEEE devices on the remote bus (in addition to the remote bus extender). The bus
extenders have no address of their own, and therefore will operate completely transparent to the system.
Be careful not to have two IEEE devices with the same address connected to either remote or local buses.
Failure to do so will result in the bus 'locking up' when one of the devices is accessed.
2.7 Speed Considerations
The Extender488/HS bus extenders operate transparently to most IEEE 488 applications.
However, since there is an inverse relationship between the data transfer rate and the cable length, the
response time for bus transactions may be affected. The following information is provided so that you can
determine if some modifications may be needed to your application.
As the length of the cable linking the two bus extenders is increased, the data transfer rate will
decrease. A graph showing the typical data transfer rate as a function of distance is shown on the next
page.