Status Byte Register; Reading The Status Byte Register - Fluke 8845A Manual

8845A/8846A
Programmers Manual

Status Byte Register

The Status Byte Register (STB) is a binary-encoded register that contains eight bits. Note
that the Service Request Enable Register (SRE) uses bits 1 through 5, and bit 7 to set, the
request service (RQS) bit 6, as enabled by the SRE. When the RQS bit is set true (l), the
Meter sets the SRQ line true (1), which generates a service request. The eight bits of the
Status Byte Register (as read by the *STB? command) are described in Table 7.

Reading the Status Byte Register

The host can read the Status Byte Register by performing a serial poll, or sending the
Meter a *STB? query. The value of the status byte is not affected by the *STB? query.
When the Status Byte Register is read, an integer is returned. This integer is the decimal
equivalent of an 8-bit binary number. For example 48 is the decimal equivalent of the
binary 00110000, and means that bit 4 (Message Available) and bit 5 (Standard Event)
are set to "1".
If the status byte is read by serial poll, bit 6 is returned as a request service (RQS); if it is
read with an *STB? query, bit 6 is returned as Master Summary Status (MSS).
EXAMPLE
*STB?
26
Table 6. Description of Bits in the Questionable Data Register
Bit No.
0
1
2 – 8
9
10
11
12
13
14 – 15
Reads the Status Byte Register. Assume that "32" is returned. Converting 32
to the binary 00100000 indicates that bit 5 (Standard Event) is set to 1. To
determine the event status, you would have to read the Standard Event
Register in the same manner, using the *ESR? command.
Name
Voltage Overload
Current Overload
Not Used
Ohms Overload
Not Used
Limit Test Fail Lo
Limit Test Fail Hi
Remote Mode
Not Used
EXPLANATION
True (Set to 1) Condition
Input voltage has exceeded the
upper limit of the range.
Input current has exceeded the
upper limit of the range.
The resistance measurement has
exceeded the upper limit of the
range.
The measurement is below the
low end of the test limit.
The measurement is above the
high end of the test limit.
The Meter is set in remote mode.