Agilent Technologies L4400 manual Basic Digital I/O Operations, Channel Numbering and Width

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

Basic Digital I/O Operations

Channel Numbering and Width

The digital channels are numbered by bank; 101 through 104 and 201 through 204 for banks 1 and 2 respectively.

Using SCPI commands you can group digital I/O channels together to allow 16- or 32- bit operations. The first and third channels on a bank can be control channels. Width and direction of the memory operations are controlled by the width and direction of the first channel on the bank (i.e., 101 or 201). In the SCPI language for the L4450A, BYTE refers to 8- bit operations, WORD refers to 16- bit operations, and LWORd refers to 32- bit operations.

This diagram illustrates how the channels are numbered for each configuration.

		Bank 1				Bank		2
				Channel
BYTE (default)	101	102	103	104	201	202		203	204
	8-bits	8-bits	8-bits	8-bits	8-bits	8-bits	8-bits		8-bits
WORD	101		103		201		203
	16-bits		16-bits		16-bits		16-bits
LWORd	101				201
	32-bits				32-bits

Reading Digital Data

The simplest way to read a digital channel is using the MEASure:DIGital? query. This query sets the channel to be an input channel and sets all other channel parameters to the default settings.

For example, sending the following SCPI command to the L4450A will read the value of the 8- bit channel 102. An unsigned integer value is returned that represents the state of the 8 bits on channel 102.

MEAS:DIG? BYTE, (@1102)

By adding parameters to the command, you can set the channel width, threshold, and polarity for read. For example, sending the following SCPI command you can read the 32- bit channel 201.

MEAS:DIG? LWOR, 2.5, NORM, (@1201)

200 L4400 User’s Guide