IEEE 488 INTERFACE
Figure 3-4. IEEE-488 Connector Location
NOTE
The IEEE-488 bus is limite~d to a maximum oft I5
devices, including the controller. The madmum
cable length is 20 meters, or 2 meters times the
number of devices, which ever is less. Failure to
observe these limits may result in erratic bus
operation.
Custom cables may be constructed by using the infoqna-~~
tion in Table 3-2 and Figure 3-5. Table 3-2 lists the contact
assignments for the bus, and Figure 3-5 shows the contact
CMfiglX&iO*.
CAUTION
IEEE-488 common is connected to digital com-
mon. Maximum voltage between digital com-
mon and earth ground is 30V.
CONTACT 12
7
,- CONTACT 1
I
CONTACT24
J
COKTACT-13
Figure 3-5. Contact Assignments
Table 3-2. IEEE Contact Designations
contact
Number
1
z
4
5
6
i
9
10
11
I.2
13
14
El
17
18
I.9
20
21
z
24
IEEE-488
Designation
DIOl
D102
D103
DIO4
EOI (24)
DAV
NRFD
NDAC
EiJ
P;TN
SHIELD
D105
D106
D107
DIOS
REN (24Y
Gnd, ‘(SF
Gnd, (7)*
Gnd, (8)
Gnd, (9)*
Gnd, (lo)*
Gnd, (ll)*
Gnd. LOGIC
Type
Data
Data
Data
Data
Management
Handshake
Handshake
Handshake
Management
Management
Management
Ground
Data
Data
Data
Data
Management
Ground
Ground
G:ound
Ground
Ground
Ground
Ground
*Numbers in parentheses refer tosignal ground return of
referenced contact number. EOI and REN signal lines
return on contact 24.
3.4 INTERFACE FUNCTION CODES
The interface function codes, which are part of the
IEEE488 standards, define an instrument’s ability to sup-
port various interface functions, and they should not be
confused with prograrmning commands found elsewhere
in this manual. Interface function codes for the Model 199
are listed in Table 3-3 and are listed for convenience on the
rear panel adjacent to the IEEE-488 connector. The codes
define Model 199 capabilities as follows:
SH (Source Handshake)-SHl defines the ability of the
Model 199 to properly handshake data or command bytes
when the unit is acting as a source.
AH (Acceptor Handshake)-AH1 d&es the ability of the
Model 199 to properly handshake the bus when it is ac-
ting as an acceptor of data or commands.
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