Keithley 6485 Instruction Manual page 245

Model 6485 Picoammeter Instruction Manual
The various bits in the status byte are described below:
Reading Overflow — Set when an overrange input is applied to the instrument.
Data Store Full — Set when the number of readings stored is equal to the buffer size.
Reading Done — Set when the instrument has completed the present conversion and is
ready to take another reading.
Busy — The instrument is still executing a prior command and is not yet ready to accept a
new command.
IDDCO — An illegal command option such as R8 has been sent. This bit is cleared when
the status byte is read.
IDDC — An illegal command will set this bit. For example, S1 is illegal since no such let-
ter exists in the command set. The IDDC bit will be cleared on a reading of the status byte.
Not in remote — Model 6485 in local mode of operation.
NOTE
Table D-2
Status byte and mask interpretation
Bit
0 (LSB)
Once the Model 6485 has generated an SRQ, its status byte must be read to
clear the SRQ line. Otherwise, the instrument will continuously assert SRQ.
The Model 6485 may be programmed to generate an SRQ for more than one
condition simultaneously.
Bit 5=0 (Data Conditions)
Overflow
1 Data Store Full
2 N/A
3 Reading done
4 Busy
5 Data
6 SRQ
7 N/A
DDC Emulation Commands
Bit 5=1 (Error Conditions)
IDDCO
IDDC
No remote
N/A
N/A
Error
SRQ
N/A
D-13