Srq Mask (M) And Serial Poll Byte Format - Keithley 595 Instruction Manual

IEEE-488 PROGRAMMING
4.9.20 SRQ Mask (M) and Serial Poll Byte Format
Purpose
Format
Parameters
Description
The M command selects which condition(s) will cause the the instrument to-assert
the SRQ (S&%e Request) line to the bus controller.
Mn
n = 0 Clear SRQ mask
n = 1 Reading overflow
n = 2 Not used
n = 4 Staircase done
n = 8 Reading done
n = 16 Ready
n=32Error
SRQ Mask-The Model 595 uses an internal mask twdetermine which conditions
will cause an SRQ to be generated. Figure 4-7 shows the general format of this mask,
which is made up of eight bits. The SRQ mask has the same general format as the
serial poll byte (described below) except for the fact that bits 6 and 7 are not used
in the SRQ mask.
The Model 595 can be programmed to generate an SRQ under one or more of the
following conditions:
1. Jf a reading overflow occurs (Ml).
2. When a staircase sweep is complete (M4).
3. When a reading is done (MS).
4. When the instrument is ready to accept bus commands (M16).
5. When an error condition occurs (M32)
Note that the instrument may be programmed for more than one set of conditions
simultaneously. To do this, simply add up the decimal bit values for the required
SRQ conditions. For example, to enable SRQ under reading overflow and staircase
done conditions, send M5X. To disable SRQ send MOX.
Once an SRQ is generated, the serial poll byte can be checked to determine if the
Model 595 was the instrument that asserted SRQ.
Serial Poll Byte Fmmat-The serial poll byte contains information relating to data
and error conditions within the instrument. The general format of this status byte
(which is obtained by using the serial polling sequence, as described in paragraph
4.8.8) is shown in Figure 4% Note that the various bits correspond to the bits in the
SRQ mask as described above.
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