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Anleitung Agilent Technologies, modell 6628A

Hersteller: Agilent Technologies
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This chapter contains all the information required to control your power supply remotely and discusses in greater detail how each of the commands can be implemented. The material covered is intended for any controller capable of using the GP-IB interface functions mentioned in Interface Functions on page 63. Four major sub-sections are discussed. These are: 1. GP-IB Operation 2. Programming Syntax 3. Initial Conditions 4. Power Supply Commands The GP-IB section briefly describes the GP-IB interface functions to get you acquainted with remote programming using the GP-IB. Under Programming Syntax, the syntax of all commands, the numeric data formats and the programmable ranges for all models are given. Initial Conditions highlights the initial values of all the parameters at power-on. Power Supply Commands will describe all the commands which can be used to program the supply’s functions including status reporting, error handling, protection features, and voltage and current programming. The power supply commands are summarized in Appendix C. The examples are written in a generic form to make adaptation to your controller easy. You should be familiar with the use of your controller and its instruction set and how the power supply commands can be incorporated in your controller commands. If you are not familiar with the operation of the power supply, you are advised to read through Chapters 2 through 4 first. GP-IB Operation Interface Functions Remote control is implemented by the GP-IB. It enables instructions to be sent from an external computer equipped with a GP-IB interface. The power supply implements the following IEEE-488 Interface Functions: SH1 - Source Handshake SR1 - Service Request AH1-Acceptor Handshake RL1 - Remote/Local T6 -Talker RL1 - Parallel Poll L4 - Listener DC1 - Device Clear The source handshake, acceptor handshake, talker and listener functions are implemented by the interface circuits of the power supply and the controller. The ADDR annunciator indicates when the power supply is addressed to listen or talk. (The talker function includes the Serial Poll, see page 64). Service Request. This is a message which can be initiated by the power supply to request service from the controller. When the supply is requesting service, it asserts the service request (SRQ) line on the GP-IB to interrupt the controller providing the controller is configured to service interrupts. A service request can be generated whenever there is a fault on one of the outputs (up to 4 outputs), a programming error has occurred, or at power on providing certain commands are sent. Service request commands are discussed in detail in Service Request Generation on page 79. The SRQ annunciator on the front panel display is turned on when the power supply is requesting service from the computer and remains on until the controller conducts a serial poll. A serial poll removes the service request and turns off Remote Operation 63 the SRQ annunciator regardless of whether the condition that caused the service request continues to exist. The service request is also removed when you send the "CLR’’ command (see page 76). Remote/Local. The power supply can receive programming information either from the GP-IB (remote) or from the front panel (local). When the power supply is in remote, the state of the supply cannot be changed by using the front panel keys, although the LCL key will remain enabled. Remote operation takes precedence over local operation, hence if the supply is accepting commands remotely and you attempt to change it to local operation, the supply will not allow any local settings and will remain in remote. You can prevent the front panel from sending programming information by sending the local lockout command. This command is sent only from the GP-IB. If you change from local to remote or vice-versa, there will be no change in the programmed settings. Parallel Poll. Parallel Poll allows the controller to receive at the same time one bit of data from each of up to eight instruments connected to the bus. Agilent power supplies designate bit #6, the RQS bit of the serial poll register for this operation. By checking the status of this bit, the computer can quickly determine which instruments on the bus requested service. Once an instrument is identified, the computer can perform a serial poll to find out the exact cause of the request. Parallel Poll does not reset this service request bit (RQS) in the power supply. Note IEEE-488 does not define what data an instrument should put on a bus in response to parallel poll. Many instruments such as Agilent Technologies power supplies indicate the state of their RQS bit, but the operator should not assume that all instruments on the bus respond to parallel poll with their RQS bit. Unless remotely configured, the power supply will respond with a 1 on one of the GP-IB data lines if it is requesting service and its address is between 0 and 7. Addresses 0 through 7 define whic...