Specifications

28 Chapter 2
Outline of Remote Control
Outline of GPIB remote control system
The sizes and configurations of possible GPIB systems
• A maximum of 15 devices can be connected to one GPIB system.
• Keep the length of cable between devices within 1 m. The total length of connecting
cable in a single GPIB system should not exceed 2 m × the number of connected
devices (the controller is counted as one device). Also, you cannot construct a system
having more than 20 m in total cable length.
• The number of connectors on a single device should not exceed 4. More than that will
cause strain on the connector parts, which could lead to equipment breakdown.
• The pattern of connection can be star topology, linear topology or a combination of
both. However, loop topology cannot be used.
Controller
The device that allows talk (data output) or listen (data receipt) by the GPIB device is
called the controller.
An active controller can control other devices on the bus (if multiple controllers are
connected). Only one controller can be active at any one time. By executing the pass
control, the active controller can pass the controlling right to another controller (pass
control function).
NOTE When the E4991A is used in system controller mode, the controlling right cannot be passed
to another controller or cannot be received from another computer because the E4991A
does not support the pass control function.
Device selector
Device control of GPIB is performed by sending a command by the active controller. The
active controller can choose the target device by specifying the device selector.