MODEL DG535 Digital Delay / Pulse Generator - SLAC

Bit 6: This bit is set if the RC (recall storedsettings) command finds that the stored valueshave been corrupted. A checksum is done on thesettings when they are stored, and if thecomputed checksum on recall does not match,then the command is aborted and this error bit isset.Bit 5: This bit is set if an attempt is made to seta delay to a value below zero or above999.999,999,999,995 seconds. Because thedelay channels may be linked to each other,changing a delay to an allowed value may causeanother delay to exceed the allowed range ofvalues.Bit 4: This bit is set if an attempt is made to linkdelays in an illogical fashion. For exampleA=B+1.000 and B=A+2.000 is a conditionwhich clearly cannot be satisfied.Bit 3: This bit is set if the instrument is not inthe correct mode for the command that was sent.For example, if the instrument set to trigger onthe internal rate generator, the SS (single shot)command will be ignored and cause bit 3 to beset.Bit 2: This bit is set if the value of a parameterexceeds the allowed range for that parameter.For example, if the command "TL 20.0" is sent,the command will be ignored and bit 2 will beset (because the trigger level may only be setbetween ±2.56VDC).Bit 1: This bit is set if too many or too fewparameters are sent with a command.Bit 0: This bit is set if the command iscompletely unrecognized.ISReturns the Instrument Status byte. Thedefinition of the instrument status byte is givenbelow. Example: if the trigger rate to the DG535is too high, bit 4 of the instrument status bytewill be set. Sending the command "IS" willreturn the value "16" (if no other bits have beenset). All of the bits in the instrument status byte,except for the BUSY bit, are latched, ie., if atrigger rate error is detected at any time, that bitwill stay set until the "IS" command is sent. Allbits, except the BUSY bit, will be reset to 0 afterthe "IS" command is executed. (See the IS icommand to test one bit of the Instrument Statusbyte.)IS iReturns bit i of the Instrument Status Byte.Example: the command "IS 4" will test bit 4, the"trigger rate too high" bit. The value "1" will bereturned if a trigger rate error occurred since the lasttime the "IS" or "IS 4" command was sent. If noerror had occurred, then the value "0" will bereturned.INSTRUMENT STATUS BYTE DEFINITIONBit Description7 Memory contents corrupted6 Service request5 Always zero4 Trigger rate too high3 80MHz PLL is unlocked2 Trigger has occurred1 Busy with timing cycle0 Command error detectedBit 7: This bit is set if the instrument settings werecorrupted since the last time power was removed.The processor computes a checksum of RAMcontents, which contain the instrument settings,when a power supply dropout is detected. Thechecksum is again computed on power-up. If thechecksums do not match, then the default settingsare used (see CL command for default settings) andthe message "Memory Failure" is displayed. Adefective Lithium battery or very noisy ac linevoltages may cause "Memory Failures" to occur.Bit 6: This bit is set if the unit is currentlyrequesting service of the GPIB controller. A servicerequest may be generated by a variety of conditionsas specified by the service request mask. This bitallows the controller to see if this instrument wasthe one that asserted the service request line on theGPIB.Bit 4: This bit is set if the trigger rate is too fast. Theinstrument requires one microsecond after the lastdelay has finished to reset all the delay channels. If atrigger comes during this time, then the front panelRATE LED will be turned on and bit 4 will be set.Bit 3: This bit is set if a gross error is detected in the80MHz PLL. This can happen if the rear panelswitch is set to EXT reference, and the applied11