Agilent Technologies 87130A manual Drive Pulse and Sensing, Sensing Disabled, Sensing Enabled

Drive Pulse and Sensing

Introducing the 87130A Attenuator/Switch Driver

Features of the Attenuator/Switch Driver

The attenuator/switch driver can deliver 500 mA, 24 Vdc current pulses to 31 individual switch sections and up to a total of 248 switch sections by the addition of external 84940A driver boards (or driver boards inside externally connected equipment such as switch matrixes). These low impedance pulses can be adjusted for pulse width in order to optimize switching speed. Pulse width and sensing delay can be set from 0.005 to 1.275 seconds.

Sensing Disabled

Each switch coil is internally connected to the + 24 V bias supply. A power transistor on the driver board supplies the ground that will activate the switch coil. The controller assembly actuates the transistor for a predetermined time that is set by the :WIDTh command. (Refer to “:WIDTh” on page 4-67.) The default setting is 30 ms.

Sensing Enabled

For switches that can be sensed, the switch coil is internally connected to the

+24 V bias supply via a dc switch that removes the bias from the activated coil after the switch has changed position and applies the bias to the opposite coil. By monitoring the presence of this bias through the opposite coil, the switch controller can determine the switch position.

After the initial 30 ms closure pulse, an additional 20 ms time is allowed for the sense lines to settle. At this time an error and a programmed position check are performed.

The power supply allows the switch driver four switching operations at the same time. This means that at the default setting, seven groups of four switches and one group of three switches will each take 50 ms to switch and verify. This results in a default switching speed of 0.4 seconds for 31 relays with sensing enabled. Refer to “Example Speed Calculation” on page 4-74for more information.

Agilent 87130A Operating and Service Manual 1-3