Using the Serial Port

DB-9 male serial cable
Serial cable from

Maybe you just bought a Raytech table. Maybe you’ve had one for a few years now. If you’re ready to connect your table to a PC, this page will help.

What cable do I need?

The answer to this question depends on which readout your table has. In all cases, you’re going to connect to a serial port on the PC. If your PC doesn’t have a built-in serial port, you can use a USB serial adapter to create one.

Heidenhain ND 200, 700, and 900 series readouts

DB-9 null modem adapter
Null modem adapter from

If you have a Heidenhain readout in one of these series (ND 221, ND 780, ND 920, etc.) you will need a null-modem cable or adapter. Normally, serial cables are wired straight through. Pin 1 on one end is wired to pin 1 on the other end. Pin 2 goes to pin 2, etc. In a null-modem situation, pins 2 and 3 cross over, so pin 2 on the readout end goes to pin 3 on the PC end and vice versa.

Heidenhain ND 1400 and Metronics QC 300 readouts

On these readouts, the serial port is a standard port, so a straight serial cable will work, as long as the gender of the connectors match up to the PC and readout.

Older Metronics QC 3000 readouts

These require special pinning to connect to the serial ports. On top of that, these readouts are obsolete and unrepairable. If you have one of these and are using it often, you may want to contact us about upgrading to the ND 1400. It’s better to do it on your time schedule than get stuck doing it when the screen or CPU board fails.

What are the serial port settings?

This, like the cable, depends on which readout you have on the table. Listed below will be the default settings for these readouts when they leave Raytech.

Heidenhain ND 200, 700, and 900 series readouts

On older readouts, some of these settings weren’t adjustable. On newer readouts, they are. But, for the sake of consistency, we use the same settings on new readouts as we did on older readouts. They are:

  • 9600 baud
  • 7 data bits (sometimes called word length)
  • 2 stop bits
  • Even parity

Heidenhain ND 1400, Metronics QC 300 and 3000 readouts

For these readouts, the serial settings are:

  • 9600 baud
  • 8 data bits (sometimes called word length)
  • 1 stop bits
  • None parity

What about this WinWedge?

Tal Technologies supplies documentation with the software that should cover configuring the program. For the most part, the Tal manual plus the port settings listed above should get you up and running. We won’t run through all the details of configuring the WinWedge here, but will offer the basics of the settings.

  • We typically don’t assign a program for WinWedge to send keystrokes to. If you know the only thing you’ll want to collect data in is Excel, then go ahead and configure the software that way. Otherwise, WinWedge will send data to whatever window has focus.
  • We configure input records as single-fields terminated by CR/LF. One line of output from the readout becomes one data record.
  • We filter based on numeric only, which strips off the leading axis indicators and trailing unit indicators, leaving only a number. We also add preamble and postamble keystrokes, but those are specific to our software configuration for calibrating machines.

When testing, use the test mode on the WinWedge. It will be more convenient to see what’s working, and tweak things that aren’t. When everything is locked in, we often save the configuration file, and set Windows up to launch WinWedge with that configuration when double-clicked. It makes it easier for the operators to use that way.