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1.5 Responses to Interface Messages
1.5 Responses to Interface Messages
What Is an Interface Message
Responses to Interface Messages
1-6
Interface messages are also referred to as interface commands or bus commands. They
are commands that are issued by the controller. They are classified as follows:
• Uni-line messages
A single control line is used to transmit uni-line messages. The following three types
are available.
IFC (Interface Clear), REN (Remote Enable), and IDY (Identify)
• Multi-line messages
Eight data lines are used to transmit multi-line messages. The messages are
classified as follows:
• Address commands
These commands are valid when the instrument is designated as a listener or as a
talker. The following five types are available.
• Commands that are valid on an instrument that is designated as a listener
GTL (Go To Local), SDC (Selected Device Clear), PPC (Parallel Poll Configure),
and GET (Group Execute Trigger)
• Commands that are valid on an instrument that is designated as a talker
TCT (Take Control)
• Universal commands
These commands are valid on all instruments regardless of the listener and talker
designations. The following five types are available.
LLO (Local Lockout), DCL (Device Clear), PPU (Parallel Poll Unconfigure), SPE
(Serial Poll Enable), and SPD (Serial Poll Disable)
• In addition, listener address, talker address, and secondary commands are also
considered interface messages.
• The differences between SDC and DCL
In multi-line messages, SDC messages are those that require talker or listener
designation and DCL messages are those that do not require the designation.
Therefore, SDC messages are directed at a particular instrument while DCL
messages are directed at all instruments on the bus.
• Responses to a uni-line message
• IFC:
Clears the talker and listener functions. Stops output if data are being
output.
• REN:
Switches between the remote and local modes.
• IDY:
Not supported.
• Responses to a multi-line message (address command)
• GTL:
Switches to the local mode.
• SDC:
Clears the program message (command) being received and the
output queue (see page 5-5).
• GET:
Same operation as the *TRG command.
• The COMMunicate:WAIT command is immediately terminated.
• PPC or TCT: Not supported.
• Responses to a multi-line message (universal command)
• LLO:
Disables the LOCAL key on the front panel to prohibit switching to the
local mode.
• DCL:
Same operation as the SDC message.
• SPE:
Sets the talker function on all devices on the bus to serial polling mode.
The controller polls the devices in order.
• SPD:
Clears the serial polling mode of the talker function on all devices on the bus.
• PPU:
Not supported.
IM 704510-17E
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