3 ieee 488 bus configuration – Measurement Computing Serial488/4 User Manual
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Section 2
Getting Started
2.3
TALK
ON when the Serial488/4 is in the Talker active state, OFF when the
Serial488/4 is in the Idle or Listener active state
LISTEN
ON when the Serial488/4 is in the Listener active state, OFF when
the Serial488/4 is in the Idle or Talker active state
SRQ
ON when the Serial488/4 has generated a service request, OFF
when no SRQ is pending. (See Section 3 for more information.)
ERROR
ON when an error has occurred, OFF when no error condition
exists. (See Section 3 for more information.)
POWER
ON when power is applied to the Serial488/4 and the power switch
on the back panel is in the ON position (depressed). OFF when
power is not present or the internal fuse or power supply is faulty.
Mounted on the rear panel of the Serial488/4 are the power cable connector, the
power on/off switch, the IEEE 488 bus connector, the addressing mode/address switch
and four 9 pin Sub-D male connectors, one for each serial port.
2.3
IEEE 488 Bus Configuration
The Serial488/4 must be user-configured for proper operation over the IEEE 488
bus. Bus configuration includes selection of addressing mode, bus address, and bus
terminator. Each of these configuration selections are described below.
The Serial488/4 bus addressing mode and bus address are determined by the
eight position switch located on the rear panel (see Figure 2-1). Sw itch positions
SW1-1 through SW1-5 determine the IEEE address (0 - 30); SW1-6 and SW1-7 are
not used; SW1-8 determines the addressing mode (dual primary or secondary). SW1
is set at the factory for IEEE address 8 and dual primary addressing mode as shown in
Figure 2-2. SW1 switch settings are read only w hen the Serial488/4 is powered on
and should only be set before power is applied. If it is necessary to change the switch
setting, first be sure the power cord is disconnected from AC line. Then, with a small
flat blade screwdriver, slide each switch into the position desired. Refer to Sections
2.3.1 and 2.3.2 for a discussion of the various mode and address selections.