System SourceMeter® Instrument Reference Manual  Section 3: 
 
2600BS-901-01 Rev. B / May 2013  3-85 
 
Digital I/O configuration 
The following figure shows the basic configuration of the digital I/O port. Writing a 1 to a line sets that 
line high (~ +5 V). Writing a 0 to a line sets that line low (~0 V). Note that an external device pulls an 
I/O line low by shorting it to ground, so that a device must be able to sink at least 960 µA per I/O line. 
 
Figure 88: Digital I/O interface schematic 
 
 
Controlling digital I/O lines 
Although the digital I/O lines are primarily intended for use with a device handler for limit testing, they 
can also be used for other purposes such as controlling external logic circuits. You can control lines 
either from the front panel or over a remote interface. 
To set digital I/O values from the front panel: 
1.  Press the MENU key, select DIGOUT, and then press the ENTER key or press the navigation 
wheel  . 
2.  Select DIG-IO-OUTPUT, and then press the ENTER key or the navigation wheel  . 
3.  Set the decimal value as required to set digital I/O lines in the range of 0 to 16,383 (see the table 
in Digital I/O bit weighting (on page 3-86
)), and then press the ENTER key or the navigation 
wheel  .  
For example, to set digital I/O lines 3 and 8, set the value to 132. 
4.  Press the EXIT (LOCAL) key as needed to return to the main menu.