Hardware Interfaces  CMU 
1100.4903.12 8.4  E-8 
Interface Messages 
Interface messages are transmitted to the instrument on the data lines, with the attention line being 
active (LOW). They serve to communicate between controller and instrument. 
 
 
 
Universal Commands 
 
Universal commands are encoded in the range 10 through 1F hex. They are effective for all instruments 
connected to the bus without pervious addressing. 
 
Table 8-1  Universal Commands 
Command  QuickBASIC command  Effect on the instrument 
DCL  (Device Clear)  IBCMD (controller%, CHR$(20))  Aborts processing of the commands just received 
and sets the command processing software to a 
defined initial state. Does not change the instrument 
setting. 
IFC  (Interface Clear)  IBSIC (controller%)  Resets the interfaces to the default setting. 
LLO  (Local Lockout)  IBCMD (controller%, CHR$(17))  Locks switchover from remote control to Local 
(manual control) by means of the front panel keys 
 
 
 
Addressed Commands 
 
Addressed commands are encoded in the range 00 through 0F hex. They are only effective for 
instruments addressed as listeners. 
 
Table 8-2  Addressed Commands 
Command  QuickBASIC command  Effect on the instrument 
GTL  (Go to Local)  IBLOC (device%)  Transition to the Local state (manual control). 
 
 
Note:  The CMU can not be configured as a high-speed HS488 listener; the commands CFE 
(Configure Enable) and CFGn (Configure) are not supported.