For high-speed operation (100 K switches/sec.) the scanning list is automatically downloaded into RAM on the multiplexer module. Triggering for channel advance is from the two handshake lines on the digital bus. The scanning operation does not require any intervention from the mainframe CPU. This only applies for switchboxes or scanning voltmeter configurations that have all FET multiplexer modules. For a downloaded scan list in switchboxes, the trigger source must be TRIG:SOUR DBUS or TRIG:SOUR IMM.

Multimeter Connection Points

Analog Bus Connector

There are three places where signals on a closed channel can be measured: analog bus connector, tree terminals and direct terminals. Each of these provides a different capability for configuring the module.

The analog bus connector provides a direct connection between multiple multiplexer modules and also between a multiplexer module and HP E1326/E1411 Multimeters. A ribbon cable is used to daisy-chain multiple multiplexer modules together, and to connect a multimeter to the multiplexer modules for a scanning voltmeter. The SCAN:PORT ABUS command automatically closes the appropriate tree isolation switches to route closed channels to the analog bus. This command must be executed in a switchbox configuration. A scanning voltmeter automatically configures the multiplexer for the analog bus connector.

Tree Terminals Tree terminals provide an external connection point through the terminal modules for the signals which are on the analog bus lines. Tree terminals are the recommended connection points for connecting stand-alone multimeters and external current sources for 4-wire resistance measurements.

Direct Terminals The 16 channels are separated into two banks, Bank 0 and Bank 1. When a channel is closed, that channel is connected to a Bank Common. Channels 00 to 07 are on Bank 0 Common and channels 08 to 15 are on Bank 1 Common. The terminal module has connection points for the direct terminals, where you can measure signals on the respective Bank Commons. The banks can be isolated from each other, from the analog bus connector, and from the tree terminals with the A and B tree isolation switches.

12 Getting Started with the HP E1351A/53A

Chapter 1