Gage Interface Information

Connecting an electronic gage to SPC Express can be very simple. SPC Express allows sample information to come from:

This page deals with interfacing through the serial communications port (Comm port).

SPC Express requires that each sample value received from a gage be contained within a data transmission from the gage. This data transmission (hereafter referred to as a "record") should be ASCII data and be terminated with a Carriage Return [CR]. Each record should contain one sample value and an optional ID field. The ID field may be used if readings will be sent that belong to different characteristics. In this way, various readings can be "routed" to the correct characteristic on the screen.

As each record is received by the computer, SPC Express looks for the sample value and puts that reading into the next empty sample field of a subgroup entry form that is in the "new" mode. If a Gage ID has been specified (see below) then the sample value will be place into that subgroup only if the Gage ID matches. As soon as the last sample for that subgroup is received, the subgroup is saved to disk and also charted if a graph for that characteristic is open on the screen.




Let's say your data from your gage looks like this:

01 1.6125 inches DIA [CR]
(the above numbers are a "Ruler" and are shown for ease of counting)

Starting from the left, count the number of characters and you will see that the sample value (1.6125) starts in byte position 4 and is 6 bytes long (see Note 1 below). Enter this information on the Input Options screen. The Gage ID (DIA) starts in byte position 18 and is 3 bytes long. So enter 18 for the GageID Starting Byte and set the GageID to DIA. Then only records containing the letters "DIA" will be accepted into this characteristic.

Note 1: You can alternatively specify a 'field number' instead of a byte number by adding 700 to the field. For example, if your sample is in the 3rd field, specify 703 for the position of the sample. (Fields would usually be separated by commas.)


  1. If you're having trouble reading your gage, try running the MMS Communications Utility, MMSCOMM.EXE.   It is on your Start menu, under SPC Express for Windows.   Or better yet, run the Communications Test Utility.   It is located on the "Input & Conversion" Tab of Global Preferences.   This will let you try different baud rates, parity, etc. and see what the gage is sending.   There is a 'ruler' at the top of the Utility screen that will help you count how far over the Sample Value and GageID fields (if any) are.
  2. In rare cases, the Comm Utility will be able to read your device but SPC Express won't.   If that is the case, check to see if your system has a file called MSCOMM32.OCX and that it is registered.   You want the file dated 6/24/1998, NOT the one dated 8/21/1995.   Download MSCOMM32.OCX (06/24/1998)   (Save in windows system folder and register using REGSVR32)
  3. You can also enter TRACE=1 in the Formula field.   This will show you step-by-step how SPC Express is trying to handle your gage input.  
  4. It is also a good idea to turn on "Show gage data on StatusBar" in the Global Preferences.