SPI setup#

This page, is dedicated to the installation steps for the various tools needed to operate on the SPI. In addition, we will explain how to connect an SPI rack to your host PC. Before setting up the SPI rack, make sure that qblox_instruments Python driver is successfully installed, which follows the same process as for the Qblox Cluster, seen on the page Setup.

Setting up the SPI Rack#

In this section we will go through the connections needed to establish the Qblox SPI Rack and how to connect it to the power chain and to your PC.

Connecting the SPI components#

The components in the SPI setup are connected as seen in the schematic below.

An SPI Rack connected to a battery and via a gyrator to mains.

Important

It is important that the components are connected in the order which the schematic illustrates.

The recommended way to connect the SPI Rack to power is by connecting it via a gyrator to mains in parallel to a battery. This will ensure the system remains powered and stable while the gyrator prevents interference signals such as 50 Hz from getting to the SPI Rack by mimicking a large (~40H) inductor.

Connecting to Power#

To connect the power to the SPI rack chassis, the power chain is connected to the back of the SPI rack chassis, specifically through the connectors on the left side on the SPI rack chassis.The left side of connectors on the back of the SPI rack chassis is the mandatory supply input. This implies that the connection is established from one of the connectors on the front of the battery pack, linking the SPI rack chassis to the power chain. Which of these two connectors does not matter as the two connectors are coupled internally.

Important

If the mains supply or PSU is switched OFF while the SPI rack switch is ON, the battery will supply power to the rack and will slowly drain out the batteries. Therefore it is important to switch OFF the SPI rack if you are not using the SPI rack.
The battery must always be used in the setup. Make sure the batteries are routinely charged which may be achieved by turning the mains supply ON and turning the SPI rack switch OFF. The recommendation is to charge the battery at least once every two weeks.

Important

When connecting each component in the SPI setup, each cable has a required cable between each connection which can be seen in the following table.

Connection	Cable type	Cable length	Comments
PSU to Gyrator	Shielded DC cable	Less than 3m	Special cable, sent with the product
Gyrator to Battery	Shielded DC cable	Less than 3m	Special cable, sent with the product
Battery to Chassis	Shielded DC cable	Less than 3m	Special cable, sent with the product
C1b to C2	Displayport cable	Less than 3m	Normal displayport cable, specified less than 3m
C2 to computer	USB cable	Less than 3m	Normal USB cable, specified less than 3m
Output cable	Shielded MCX cable	Less than 3m	Specified less than 3m

Note

The cable between the gyrator and the power supply also requires a minimum of 1 meter to effectively prevent interference signals from getting to the SPI Rack. Also, ensure that the SPI Rack is not mounted in the same 19-inch rack with line-powered equipment, this includes the gyrator power supply.

To complete the whole power chain setup to the SPI rack chassis, as shown in the schematic at Connecting the SPI components, make the following connections:

Connect the external PSU to one of the connectors of the gyrator using a shielded DC cable.
Connect the second connector of the gyrator to one of the front connectors on the battery pack. The battery has two connectors on the front of the battery pack.
Connect the second connector of the battery pack to the back of the SPI rack chassis.

The connection steps between the power chain and the SPI rack chassis are now completed.

Setup with more than 5 S4gs#

Important

When housing the SPI rack chassis with more than 5 S4gs with the current SPI setup, the setup must be extended by an additional PSU and a gyrator connected to one battery pack. In this case, the additional components will be provided by Qblox. The additional PSU and gyrator will now be able to support up to 9 S4gs, where each channel on the S4g is operating at the maximum rating i.e @ 40 mA at the given output voltage range of the PSU, see External Power Supply unit.

Connecting to PC#

To make a connection between the PC and the SPI rack, we utilize the C1b module to enable the connection that is the C1b controller module and the C2 isolator box.

Make sure the C1b controller module is fully inserted in the leftmost slot of the SPI Rack.
Then, connect the C1b to the C2 Isolator box via a displayport cable.
Now, connect the C2 SPI Isolator box via a USB cable to your PC.
Finally, make sure the power switch on the back of the SPI Rack chassis is in the ON position, and the power supply is switched ON as well. The power switch of the SPI is the left side switch above the left side connector output pair. The LED on the C1b module should now turn on.

On Windows systems, the SPI rack will now show up as a COM port in Windows Device Manager, while on OSX and Linux systems, it will show up in the /dev/ directory as /dev/ttyUSB#, /dev/ttyS# or /dev/cu# (where # is a number). Please note down the COM port or /dev address as we will use it later.

We can now connect to the SPI Rack via the QCoDeS driver provided through the qblox-instruments package (see section Installation).

Communicating with the SPI Rack#

Starting the communication with the SPI Rack is done by simply instantiating an instance of the driver:

from qblox_instruments import SpiRack
# Replace COM4 with the port that your SPI rack is connected to.
# On OSX and Linux systems, this will be of the form /dev/tty## or /dev/cu##
spi = SpiRack('SpiRack', 'COM4')

For each of the modules we intend to use, we should add to the driver. This is done simply by:

spi.add_spi_module(2, "S4g") # example for an S4g on address 2