Agilent Technologies L4400 manual Interrupt Lines, Memory Output Operations

L4450A 64-Bit Digital I/O with Memory and Counter 8

Check the status of the transfer. You can use the SENSe:DIGital:MEMory:DATA:POINts? query to return the number of

samples currently in memory.

Retrieve the captured data. Set the desired memory retrieval format using the SENSe:DIGital:DATA:FORMat command. You can set the memory to be read as either LIST or BLOCk. The LIST parameter (default) returns the data as comma separated ASCII values. BLOCk returns the data in IEEE- 488 block format.

Before you can read the data in memory, you must stop the memory operations using the SENSe:DIGital:MEMory:ENABle OFF command.

Read all the captured data using the SENSe:DIGital:MEMory:DATA:ALL? query. This performs a non- destructive read of all data in the bank’s memory.

To read specific captures, use the SENSe:DIGital:MEMory:DATA? form of the command. This command takes index and count parameters to specify which data to retrieve. The oldest data in memory has an index of ‘0’. The count specifies the number of samples to read. count + index must be less than the number of captured points.

Both these data reads are non- destructive to the bank memory. To clear the memory for new data, send the SENSe:DIGital:MEMory:CLEar command.

Interrupt Lines

Each bank has an interrupt line that can be used with memory input or output operations. When a bank is set to input data, the interrupt line is an output. When a bank is set to output data, the interrupt line is set to be an input. You can set the polarity of the interrupt line for input and output operations using the CONFigure:DIGital:INTerrupt:POLarity command.

You can configure the interrupt line drive mode, output drive level, and input threshold. These parameters are set for both the handshake lines and interrupt line on a bank. See page 204 for details about setting these parameters.

Memory Output Operations

For memory output operations, the interrupt line is sensed and can be used to start or stop memory output operations. This provides a hardware means to control the data output.

The SOURce:DIGital:INTerrupt:MODE command sets how the bank will behave when using memory output. The mode can be set to one of three values:

•STARt: The memory output will begin on the rising edge of the interrupt line.

L4400 User’s Guide 213