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Remote Operation74
Figure 5-3. Functional Relationship of Status Registers
The supply has one serial poll register which services all outputs and provides the user with other power supply status-
related information as discussed on page 75.
Status Register. Each output channel of the power supply maintains its present status in an 8-bit register. This status
register reports the status of the output channel whenever it is queried. A "1" in any of the bit positions indicates that the
condition is true. As long as the condition continues to be true, the bit will remain set. Assignments for the bits are shown
in Table 5-5.
Decoding of the reading is based on the weighted number placed on each bit of the 8-bit status registers. For example, bit
position 5 in the register has a bit weight of 32 (see Table 5-5). Each bit is assigned to a particular condition and the
corresponding bit weight is used to identify that condition. When set, bit 5 indicates that the associated output is in the
unregulated state. If this is the only bit that is set, the number 32 will be returned when the output's status register is
queried.
Table 5-5. Bit Alignment for the Status, A Status, Fault, and Mask Register
Bit Position 7 6 5 4 3 2 1 0
Bit Weight 128 64 32 16 8 4 2 1
Meaning CP OC UNR OT OV -CC +CC CV
Where
CV = Constant Voltage Mode
+ CC = Positive Constant Current Mode
- CC = Negative Current Limit Mode
OV = Overvoltage Protection circuit tripped
OT = Over Temperature Protection circuit tripped
UNR = Unregulated Mode
OC = Over Current Protection tripped
CP = Coupled parameter (See Note)
Note: When the range is automatically switched as discussed on page70, the CP bit is set. It is cleared when you send a
voltage or current value that causes no range change.
To query an output channel for its status, you must specify the output channel. For example, to find out the status at output
2 send the following query and address the supply to talk:
STS? 2
Accumulated Status Register. Each output channel of the power supply also maintains a cumulative status in its
accumulated status (astatus) register. This register records every status condition the power supply output entered since it
was last queried. When queried, it returns a decimal number which is decoded as shown below. The astatus register is
reset to the present value of the status register after it is queried. The bits are assigned as in Table 5-5. Here is an example
to help you decode the decimal number (from 0 to 255) returned when the astatus register is queried. If the output channel
was in overvoltage since the last reading of the astatus register and that channel is presently operating in constant voltage
mode, the reading you will get when you query the register will be 9. To decode this we use table 5-5.
9 = 8 + 1
OV + CV
For example, to query the astatus register of output 2, send the following query and address the supply to talk.
ASTS? 2