UWMLSC > Beowulf Systems > Medusa

Using the 22-805 Multimeter With Linux

To use the Radio Shack 22-805 Multimeter with Linux, a simple application called multimeter can be used. Download the source from here (version 0.0.5) or from the creator's page at http://www.home.pages.at/linux/.

Unzip and unpack the source, then make it. To run:

multimeter -6 [-l] [-i interface] [-h]

The -6 flag makes multimeter communicate at 600 baud, which is required for the 22-805. The -l flag instructs multimeter to loop forever. The -i interface flag will specify which serial port to use, where interface is /dev/ttySX, where X is the number correlating to the desired serial port. Multimeter uses serial port 2 (/dev/ttyS1) by default - if that is the port you are using, you won't need to use this flag. The -h flag brings up a help screen which has additional flags that can be used.

The highest rate the 22-805 seems capable of communicating (at least with the multimeter software) is at one transmission per second.

If you wish to write your own code for the 22-805 instead, you'll need the following information relating to the 22-805 (copied from its instruction manual):

Communication Parameters

Transmission rate: 600 baud
Character coding: 7-bit ASCII
Parity: None
Stop Bits: 2

Data Format

The data format consists of a frame of 14 bytes. The frames are set as follows:
BYTE)      1 2 3 4 5 6 7 8 9 A B C D E
Example 1) D C   - 3 9 9 . 9     m V CR
Example 2) O H     3 9 . 9 9 M o h m CR

$Id: multimeter_instructions.html,v 1.1 2002/02/07 00:03:00 duncan Exp $
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