Service Requests - Fluke 8845A Manual

Example
+1.0071E+21 CR LF
As with local operation, none of the errors are latching except for ERROR 31. If the mA
DC or mA AC function is requested while the FRONT/REAR switch is in the REAR
position, ERROR 31 will persist until the switch is set to FRONT or another function is
selected.
To check for an error condition, test whether the output buffer data is greater than or
equal to +1E+21, or test the Any Error bit (bit 6) in the serial poll register.
Status Data
Status data is the output in response to G0, G1, G3, G4, G5, G6, G7 and G8, commands.
The data is formatted as shown in Figure 7, and is interpreted in Table 30. Examples of
status data can be found in the description of the Get commands.
The SRQ mask loaded by the G1 command consists of two integers plus terminators. All
other status data is always a four-digit integer plus terminators. The terminators LF (Line
Feed) and CR (Carriage Return) each add an extra character when enabled.
The Meter begins some status data with a leading ASCII one (1) or a one and a zero (10).
This prevents the controller from suppressing any leading zeros present in the output string
of the Meter. It also gives a uniform four-character length to all instrument configuration
data.
Status data from the Get commands reflects the status of the Meter at the time the command
is executed at its place in the input command string.
Output Priority
Since only one output string is allowed per input command string, the Meter gives
priority to some types of data over others. An input command string may call for more
than one output string. (For example, an input string may contain a Get command but
also cause an error message.) However, the output buffer is loaded with only one output
string. That string is selected according to the following priority:
1. Status data (from G0, Gl, G3, G4, G5, G6, G7 and G8)
2. Error messages (if an error exists)
3. Numeric data
This means that an error message always overrides numeric data, but status data is sent
even in the presence of an error. However, the status data does not clear the error
message; the error message is sent the next time numeric data is requested.

Service Requests

Service requests let bus instruments get the attention of the system controller. The
requests are sent over the SRQ line (one of the IEEE-488 bus lines). If more than one
instrument on the bus is capable of sending service requests, the controller can learn
which one made the request by taking a serial poll. Each device (including the Meter)
responds to the poll by sending the contents of its serial poll register. The serial poll
register indicates whether or not the device requested service, and if so, the reason for the
request.
The Meter may be programmed to make a service request on user-specified conditions.
The conditions are specified by entering a value for the service request mask (SRQ mask)
Explanation
ERROR 71: Syntax error in device-dependent
command string.
Remote Operation
FLUKE 8842A Emulation Mode
91