3-5
3
3.3.2 Event Status Register
The Event Status Register reports events that are common to all 488.2 devices.
This includes events such as selftest errors, command errors, execution errors,
power on and operation complete. The Power-on event occurs at power turn-
on and can be used to signal a power off-on occurrence. The Modbus Error
is included in the Event Status Register. Bit 6 is set when the Modbus Error
Register is loaded with an error value. The 488.2 Operation Complete event
has no meaning for the 8099.
TABLE 3-1 ESR BIT DEFINITIONS
Bit Event
Description
7
PON
The Power-on event occurs at power turn-on and can be used to signal
a power off-on occurrence.
6
Modbus Modbus Error detected. Reading the Modbus Errror Register clears
Error
this bit.
5
Cmd
Command Error
4.
Exc
Execution Error includes EDR not set and missing listen hand-
shake.
3
Flash
Flash data corrupted.
2
Query Query error, data not read or read attempt with no data.
1
EDR#2 External Data Ready Flip-flop #2
0
OPC
Operation Complete has no meaning in the 80x3s.
The Event Status Register is read with the
*ESR?
query and cleared with the
*CLS
command. Use the
*ESE
commands to set the Event Status Enable
Register as shown in the following example:
*ESE 60
'enables error bits 2 through 5 for errors
*ESE 124
'enables error bits 2 through 5 and the EDR bit
*ESE?
'queries the enabling register setting
3.3.3 Modbus Error Register
The Modbus Error Register reports a decimal value of the last error detected
with the Modbus message transmission or reported back from the Modbus slave
device. This register is cleared when read by the Modbus E? command. The
*CLS and *RST commands have no affect on this register. Refer to Table 3-5
for the Modbus Error Register values. The following commands will generate
a Service Request when a Modbus error occurs: