Troubleshooting and Diagnostics 4
34980A Service Guide 109
34933A Dual/Quad 4x8 Reed Matrix
Using program commands or the front panel of the 34980A, you can configure the
34933A dual/quad 4x8 reed matrix module for differential (2-wire) mode or
single-ended (1-wire) mode.
The 34933A module contains 100
in-rush resistors that are used to protect the reed
relays from reactive loads. If you have applications where in-rush resistors interfere with
measurements, connections are provided on the terminal blocks for you to bypass the
in-rush resistors that are located on the columns.
Two-Wire Mode
In 2-wire mode, the 34933A module contains two matrices, each with 32 2-wire
crosspoint non-latching reed relays organized in a 4- row by
8-column configuration. Every row and column are made up of two wires each, a high
(H) and a low (L). Each crosspoint relay has a unique channel number representing the
row and column that intersect to create the crosspoint. For example, channel 308
represents the crosspoint connection between row 3 and column 08 (all columns
consisting of two digits; in this case the digits are 08). See the simplified schematic on
page 110.
One-Wire Mode
In 1-wire mode, the 34933A module contains four matrices (1 through 4), each with 32
1-wire crosspoint non- latching reed relays organized in a
4-row by 8-column configuration. Every row and column has one wire each. Each
crosspoint relay has a unique channel number representing the matrix, and the
single-wire row and column that intersect to make the crosspoint. For example, channel
218 represents Matrix 2, row 1 and column 8. See the simplified schematic on page 111.
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