SECnON 4
IEEE-488 Reference
Instrument
1
%ue 4-10. IEEE Connections
I
4. Make certain that the other end of the cable is prop-
erly connected to the controller. Most controllers are
equipped with an IEEE-488 style connector, but a
few may require a different type of connec!ing cable.
Consult the instruction manual for your controller
for the proper connecting method.
/-
IEEE Connector
I
FigureP11.
1EEE488ConnectmLocdion
NOTE
The IEEE-488 Bus is limited to a maximum of
15
devices, including the controller. The maxi-
nvxn cable length is20-meters, or two meters
times the number of devices, whichever is
less. Failure to observe these limits may result
in erratic bus operation.
Custom cables may be constructed by using the informa-
tion in Table 44 and Figure 412. Table 44 lists the con-
tact assignmenk for the bus, and Figure 412 shows the
contact configuration.
CAUTlON
IEEE-488 common is connected to digital
common. Maximum voltage between digital
common and earth ground is 3OV.
Finn 4-12.
Contact Assignments
4.5 PRIMARY ADDRESS SELECTION
The Model 4&X6/487 must receive a listen command be-
fore responding to addressed
cwxman
ds. Similarly, the
unit must receive a talk
co
mmand before trsnsmitting
da&.TheMode1486/487isshippedfTomthefactorywith
a programmed primary address of 22.
The primary address may be set to any value between 0
and30aslongasaddressconflictswithotherinsinunents
are avoided. Note that controllers are also given a pri-
mary address, so do not use that address either. Most fre-
quently, controller addresses are 0 or 21, but you should
consult the controller’s instruction manual for details.
Whatever primary address you choose, you must make
cerkin that it corresponds with the value specified as
part of the controlleis programming language.
To check the present primary address or to change to a
new one, perform the following procedure:
1. PresstheMENubuttonrepeatedlyun~theprimary
address is displayed. For example, if the in.sPxuxnent
is set to primary address 22, the following message
will be displayed:
IEEE-488
ADDR 22
2. To retain the displayed address, press SI-lIFI and
then MENU to exit from the menu.
4-47
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