Many researchers requested the ability to share information in real time. At CONTEC, we can use our extensive experience in developing measurement and control equipment and network devices to solve problems like these. The GPIB standard limits the number of devices that can be connected in a single system to 15 including the controller.
It is not possible to connect more than this number of devices in a single system. There is a high degree of freedom in device connection methods, and devices can be connected in a daisy chain or star arrangement, or in a combination of the two. Devices must not be connected in a loop arrangement. Daisy chain connection. Star connection. Caution: Devices must not be connected in a loop arrangement. Cables between devices may be up to 4 m long. The maximum cable length that can be used to connect devices to each other in a single system is 2 m x no.
However, many measuring instruments have a slow communication speed, and the communication speed of devices connected on the same bus will be limited to that of the slowest device. Of the devices connected on a bus, devices that receive data are called "listeners," while devices that send data are called "talkers. The device that manages the whole system is called the "controller", which is normally a computer PC.
As the name suggests, the master is the device that has the power to make decisions regarding GPIB communication command transmission, etc. When configuring a system there must be one master and at least one slave. When controlling a measuring instrument, the PC acting as the controller is the master. Each device connected to a GPIB system has a unique address within the system that is used to identify it.
A user-assigned address is called "my address. Device addresses for the same system can be set freely from 0 to 30, but must not overlap with other addresses. A handshake is a communication method wherein a signal is sent from the sender to the receiver saying, "I'm sending data. By repeating this process, the sender and receiver transfer data while checking that it is being sent and received.
Handshake communication allows GPIB to achieve highly reliable data transmission. To prevent data from colliding, the number of devices on a GPIB bus line that can send data at any point in time is restricted to one. The device that achieves this is the controller. The controller mainly performs the operations below.
GPIB signal lines are comprised of eight data lines, three handshake lines, and five management lines. Connector pin assignments are standardized as shown in the pinout below. It is especially important to understand the role of the management bus lines that are required when putting together a GPIB program.
GPIB connector pinout. Management bus lines are used to efficiently control each device connected to the bus line, and manage the flow of information. They play an important role in controlling GPIB devices. Signal lines other than data lines all consist of a ground line and a twisted pair. Cables and connectors used in GPIB applications are shielded, and provide excellent noise resistance.
To control GPIB devices via a program and receive data, having an understanding of how SRQ service requests and polling work in addition to how management bus lines operate, will allow you to create efficient programs.
SRQ is a function that allows a device to send an interrupt request to the controller to let it know that an error has occurred or that the device is ready to send, and so on. If an SRQ request occurs, the SRQ line switches to true, which tells the controller that a device connected to the bus is requesting a service. However, as the controller cannot know which device sent the request based solely on the SRQ request, it conducts a poll to identify the device requesting the service and check the content of the request.
Serial poll is a method whereby the controller transmits an SRQ signal serially to query each device that may be requesting a service. Polled devices send a single byte of data called a "status byte" to the controller. The controller examines the status byte of each device to determine which devices have requested a service and what kind of service they have requested.
Serial polls are generally the most common type of poll used. Collectives on Stack Overflow. Learn more. Asked 8 years, 2 months ago. Active 8 years, 2 months ago. Viewed 3k times. Is there a default way of doing this or does gpib inherently involve third party drivers? Improve this question. Johannes Johannes 5, 6 6 gold badges 53 53 silver badges 92 92 bronze badges. Always third party drivers for the GPIB board unless you're planning to support all the details of different devices out there.
Even from the same vendor you can't be sure to find an unified API for all its devices : — Adriano Repetti. Add a comment. Active Oldest Votes. Improve this answer. Community Bot 1 1 1 silver badge. Jimbo Jimbo 4, 3 3 gold badges 21 21 silver badges 44 44 bronze badges.
You have to install the GPIB driver, which is typically provided by the device vendor. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.
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