APS APS-3000P Series - Page 71

CHAPTER 5
APPLICATIONS
Entire Contents Copyright  2004 by Adaptive Power Systems, Inc. (APSI) • All Rights Reserved • No reproduction without written authorization from APSI.
APS-3000P Series 5 - 12 OM-001-03000-00P-03.9
Standard Event Status Register (SESR)
The IEEE488.2 Standard defines the Standard Event Status Register (SESR). The
SESR contains the actual status information derived directly from the instrument. The
meaning of each bit in the SESR follows:
 Bit 0: Operation Complete (OPC) bit. After the device receives the *OPC
command, bit 0 (OPC bit) will be set to 1, if the device completed the TEST
command
 Bit 1: Not used
 Bit 2: Query Error (QYE) bit. Bit 2 is used to detect if an error occurred in output
queue. Errors occur in the following situations: Either the instrument attempted to
read an empty output queue or data in the output queue was lost.
 Bit 3: Not used
 Bit 4: Execution Error bit. Bit 4 signifies an execution error in the following
situations: Either the device could not execute a valid command or the supplied
data in the command parameter was out of range.
 Bit 5: Command Error (CME). Bit 5 signifies the parser detected the command
error in the following situations: The parser detected an IE488.2 syntax error. (For
example, command format is not compatible with Listener’s format. It cannot be
accepted by the Listener.) When the device receives an unrecognized command
header, the parser should generate a command error message at bit 5.
 Bit 6: Not used
 Bit 7: Power ON (PON) bit. Bit 7 indicates that an OFF – ON transition has
occurred in the instrument’s power supply.
GPIB Data Lines
The eight data lines, DIO1 through DIO8, carry both data and command messages.
The state of the Attention (ATN) line determines whether the information is data or
commands. All commands and most data use the 7-bit ASCII or ISO code set, in which
case the eighth bit, DIO8, is either unused or used for parity.