R E M O T E O P E R A T I O N
Command Syntax
7/01
LDC-3700 Series
47
C H A P T E R
3
Status Reporting
This section contains information that is relevant for understanding instrument error and status
reporting. It also contains information regarding the use of the instrument status for generating
interrupts for interrupt driven programs or subroutines. Understanding the Operation Complete
definition for the instrument is useful for programming synchronization. The Output Off Register
section also contains information on configuring the conditions which force the laser current source
and/or TEC output off.
Event and Condition Registers
In addition to the required IEEE488.2 status reporting structures, the LDC−3700B remote interface
provides Event and Condition Registers for TEC and LASER controller operations. The Event
Registers are used to report events which occur during the operation of the LDC−3700B Series
Laser Diode Controller. Events differ from conditions in that events signal an occurrence once, and
are not reset until the Event Register is queried or the LDC−3700B Series Laser Diode Controller is
powered off. Conditions reflect the current state of the device, and therefore may change many
times during operation. Querying a Condition Register does not change its contents.
Figure 3.5 on page 48 shows the status reporting scheme of the LDC−3700B Series Controller.
Each of the registers which may be accessed by a command or query has the appropriate command
or query written above or below the register representation. For example, the LASER Condition
Register may be queried via the "LASer:COND?" query.
The condition or event registers are logically ANDed with their respective enable registers. These
bits are then logically ORed to form a summary message in the status byte for that particular
register.
Operation Complete Definition
Note that Bit 0 of the Standard Event Status Register contains the status of the Operation Complete
flag. Enabling this bit via the *ESE command allows the user to update bit 5 of the status byte.
Then, if the SRE mask has bit 5 set, and the user issues an *OPC command, the SRQ signal will be
generated upon completion of the currently processed commands. This may be used to initiate
service request routines which depend on the completion of all previous commands.
For example, the user may set the TEC output to 30 °C, enable an SRQ on Operation Complete (set
*ESE 1 and *SRE 5), and have an SRQ handling routine in the user’s software which reads a new
measurement after the 30 °C value has been reached. This allows the use of the operation
complete features of the LDC−3700B Series Laser Diode Controller, without the need for program
looping or polling which can tie up the GPIB. Operation Complete on the LDC−3700B Series Laser
Diode Controller is defined as:
•
No operations to the LASER current source hardware are pending.
•
No operations to the TEC hardware are pending.
•
No EEPROM (non−volatile) memory write cycles are in progress.
TEC:T?
NONE
Returns the TEC measured temperature value.
TEC:V?
NONE
Returns the TEC voltage measurement value.
Table 3.3
LDC−3700B Commonly Used Commands
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