Measurement Computing Isolator488 - Manual (Page 19)

Section 2 Getting Started
2.10
2.6 Operation
To begin operating the Isolator488, plug the power supply into the rear panel
jack. Apply power to the Isolator488 by depressing the rear panel power switch.
The front panel POWER LED should turn on.
If the POWER indicator does not light, there may not be any power supplied to
the interface. In this event, check to make sure the AC power is supplied to the
Isolator488, and that the power cord is properly installed into the unit. If the problem
is unresolved, refer to the Service Information section (Section 4) of this manual.
If proper operation is obtained, turn off the Isolator488 and connect the other
IEEE 488 devices to each of the Isolator488 ports. Apply power to all devices in the
system.
Once all IEEE devices have been connected and powered on, the Isolator488 will
allow the system controller to command up to 13 IEEE devices on its Controller Port
(in addition to itself and the Isolator488), and up to 14 IEEE devices on the Instrument
Port. The Isolator488 has no address of its 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 ports. Failure to do so will result in the bus 'locking up'
when one of the devices is accessed.
2.6.1 Bus Loading
The IEEE 488 specification allows for a maximum of 15 bus loads.
The Isolator488 presents one bus load on each port. Therefore, an
additional 14 devices can be placed on each the CONTROLLER and
INSTRUMENT ports. Because the IEEE controller presents one bus load,
a total of 27 instruments, printers, plotters and other peripherals can be
accessed from a single IEEE controller.