Interfacing the 310T to a PC
How to set up a 310T to communicate with a PC?The 310 poses a true challenge to the user who wishes to grab information from its serial port. On the one hand, the unit is imensely versatile having nearly 20 modes that alter its serial output. On the other, there is NO way of querying the unit to see what modes are set. To further complicate the picture, certain modes require the user to alter the interface cable else the unit will refuse to transmit. Below are a few notes and ideas to share with owners.
In all cases the interface cable will be some variety of a NULL MODEM scheme. Depending on the selection of MODES 10 or 11, user may have to cut and jumper to make the system operate. To work all this out do this test:
- Remove any interface cable from the back of the 310
- Press the print key. When you do this, one of three things will happen:
-
The display will go crazy for a second or so. This is good, It means that the 310 just transmitted its measured data via the RS232 interface.
-
The display will go crazy and freeze. This is not so good. The 310 began its transmission of data and is waiting for the PC to handshake. It's locked up. You will have to turn the unit off and then back on to unlock the processor.
- The display will simply show the last measurement - no crazy stuff. Again not so good. The 310 believes there is nothing there and ignores the print command.
Now the nuts and bolts. If you are using MODE 10, the 310 will demand that its pin 5 be at a logic 0 (0 volts) else the unit will not transmit. Under normal circumstances pin 5 measures about +5V relative to the digital ground. This is equivalent to condition 3 above. The unit simply ingores the print command.
Workaround:
In cabling, at the X-Rite end, jumper pin 5 to pin 7. Do not attach pin 5 to the distant PC. This will enable the print mode by dropping the signal to logic 0 at the X-Rite end.
If you are using MODE 11 the 310 will demand that its pin 5 be at a logic 1 (+5 volts). Generally speaking a standard NULL MODEM cable will assure this as the appropriate logic signal will be borrowed from the PC. In the above scenario (where no cable is attached) the unit will simply freeze (condition 2 above). If attaching a cable and executing the desired software does not remedy the problem, it can be solved by yet another cable patch.
Workaround:
In cabling, at the X-Rite end, jumper pin 5 to pin 20. Do not attach pin 5 to the distant PC. Pin 20 always carries a +5V signal and will thus bring pin 5 to the required level.
One of the above scenarios will get the 310 transmitting.
