3. External Connection
Notes on cable connection
The GPIB has restrictions on the number of devices connected and the cable length according to the
standard.
(1) The maximum number of interfaces (external devices) is 15, which can be connected to one system.
(2) The maximum total length of cables that can be used to interconnect a group of devices in one bus
system is “2 m x (the number of devices)” or 20 m, whichever is shorter. (JIS C1901-1987).
Note, however, the individual cables between devices must be within 4 m long. Some examples
are given below.
-
System with a total of two devices
2 m x (Number of devices = 2) < 20 m
The maximum total length of cables for this system is therefore 4 m.
3765
-
System with a total of three devices
2 m x (Number of devices = 3) < 20 m
The maximum total length of cables for this system is therefore 6 m. The two cables used in
the system must be [2 m + 4 m] or [2 m + 2 m] in length so that neither is longer than 4 m.
-
System with a total of fifteen devices
2 m x (Number of devices = 15) > 20 m
The maximum total length of cables for this system is therefore 20 m.
3765
. . .
(3) The cables in the system must not form a loop.
3765
(4) Unplug the cable from any device which is left off for some reason such as a fault.
30
GP-IB(PCI)L,
GP-IB(PCI)
