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 on page 76.

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 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 73).

Remote/Local. The power supply can receive programming information either from the HP-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 HP-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. HP 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 Hewlett-Packard 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 HP-IB data lines if it is requesting service and its address is between 0 and 7. Addresses 0 through 7 define which data line (1 through 8) the supply will respond on. If the address is set to 8 or greater, the supply will not respond unless remotely configured.

The power supply may be remotely configured to respond with a 0 or 1, on any of the data lines, to indicate that it is requesting service. This is done in accordance with IEEE-488 1978.

Serial Poll. In a serial poll, the controller polls each instrument on the bus one at time. The power supply responds by placing the contents of the eight-bit serial poll register on the HP-IB data lines. Page 75 discusses the Serial Poll Register and defines the function of each of the bits. After the serial poll, the service request is cleared and the SRQ annunciator at the front panel is reset (off). However, the condition that generated the service request may still be present. See page 76.

Device Clear. The Device Clear command is typically used in systems to send all devices in the system to a known state with a single command. It may be implemented as an addressed or an unaddressed command. The power supply CLR command performs the same function as Device Clear (see page 73).

HP-IB Address Selection

You can find out the present address or change the address of the supply by using the front panel ADDR key as described in Chapter 3. Any address 0 through 30 is a valid address. If you program an address outside this range you will get a number range error.

NOTE

Care should be taken to not select the controller address.

62 Remote Operation

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HP 6621A, 6623A, 6624A manual HP-IB Address Selection
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6624A, 6621A, 6623A specifications

The HP 6623A, 6621A, and 6624A are precision DC power supplies widely recognized for their reliability and performance in various laboratory and industrial applications. These models are part of HP's 662X series, designed to cater to the needs of engineers, researchers, and technicians who require accurate power sources for their testing and development activities.

The main features of the HP 6623A, 6621A, and 6624A include their high stability, low ripple, and excellent load regulation, ensuring that the output voltage and current remain stable during testing. The power supplies provide multiple output channels, allowing users to power multiple devices simultaneously. The flexibility in setting voltage and current levels makes these models ideal for a wide range of applications, including semiconductor testing, device characterization, and system integration.

One of the standout technologies in the HP 662X series is the use of smart design techniques that minimize noise and enhance output performance. These power supplies incorporate advanced feedback mechanisms to maintain steady output, even under varying load conditions. Additionally, they feature programmable outputs, which means users can adjust the output levels through a connected computer or control system, streamlining the testing process and improving efficiency.

The HP 6623A model offers three independent outputs, with total power capabilities of 40 watts. It includes a 0-20V output, which can deliver up to 2A of current, along with two additional outputs that are adjustable. The 6621A provides a single output option, delivering a maximum of 20V and 2A, making it well-suited for simple applications where a single power source is required. In contrast, the HP 6624A stands out with its four independent output channels, providing a total of 60 watts, making it the most versatile of the three models.

Characteristics of these power supplies include user-friendly interfaces, allowing for easy configuration and monitoring of settings. LED indicators provide real-time feedback on voltage and current levels, enabling users to quickly assess the performance of their tests. Moreover, built-in protection features safeguard both the power supply and the connected devices from overvoltage and overcurrent conditions.

Overall, the HP 6623A, 6621A, and 6624A power supplies embody advanced engineering and design, making them invaluable tools for professionals looking for high-quality, reliable power sources for their electronic testing needs.
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