Subject: Communication errors on MC20 equipped Baird spectrometers
Relevant Models: All Baird DV series spectrometers using MC20 readout system, all FSQ, all ICP using MC20 readout system, all HA10 / 12 models with MC20 upgrade.
Symptoms: At anytime during the spectrometer operation an error message “Communication Error” will be displayed on the screen. This is not a gradual problem and will occur with no warning. This means the computer has lost its ability to control the MC20 and you now have a non-functioning spectrometer. This problem needs to be solved and there is no way to run the spectrometer with communication problems.
The BAIRDAS software / computer controls the spectrometer processes, spectrometer functions and analysis data acquisition through a standard RS232 serial cable connecting the computer to the MC20.
The internal communication circuits within the MC20 are located on the MC20 Single Board Computer (SBC) and the MC20 Measure Board.
The RS232 serial cable is connected to a 55 pin connector on the back of the spectrometer (DV5 ICP and all FSQ) or directly into the same 55 pin connector on the MC20 motherboard.
All computer / MC20 communication setting are done in the BAIRDAS software. There are no physical switch settings, which need to be set or checked.
Check that the serial cable between MC20 and computer is connected tightly and in good condition.
Many times this cable will come loose from either the spectrometer or MC20. Simple problem but something most customers don’t look at.
It is also possible the serial cable or connector has been damaged. A standard 9 to 25 pin serial cable can be purchased at a computer store and used in its place. B very sure the male / female pins are correct
The 9 pin goes into the serial port of the computer and the 25 pin either goes directly into the MC20 and connects on the back of the “motherboard” or connects through a 25 pin connection on the outside of the spectrometer. In this case the inside connects to the motherboard through another 25 pin to 25 pin serial cable. All wiring is standard RS232 serial wiring. There is nothing special or exclusive to Baird design.
MC20 measure board: The most common reason MC20 for a communication problem is the MC20 measure board failing.
If a measure board is available, change measure boards and retry … there is no other way to test this board so eliminate all other normal possibilities before purchasing a new board. Antares can supply tested & refurbished board at much lower cost than a new measure board and we have them in stock.
Again there is no simple way to test this SBC except to replace it. In over 15 years working with MC20 I have only seen 2 SBC cause a communication error once. This is a very reliable board.
On the SBC the U16 and U17 chips are involved in communication between SBC and MC20. If these fail, a communication error results. It is possible to monitor inputs for correct wave timing, but not suggested.
Begin by checking AC input power to the MC20 (110 or 220 VAC and marked on back of MC20).
Mounted on the back wall of the MC20 chassis, behind the red or black screen, is the low voltage DV power supply. This PS supplies 5 VDC to the MC20 to run the electronics and 12 VDC to power other functions. Using MC20 schematics from the manual, check to be sure 5 VDC output (normally 4.75 VDC to 5.20 VDC) and 12 VDC (normally 11.8 to 12.2VDC) is correct.
If no 5 and / or 12 VDC output then check the fuses on the LVPS and replace is necessary.
Check the 110 or 220 VAC power to the input of the LVPS.
Check also the output of the torroidal (doughnut) transformer on the right wall of the spectrometer. AC voltage ratings are listed on the torroidal transformer terminal strip.
A failed serial port on the computer will cause this problem.
To test this, move the serial cable to the 2nd serial port.
The BAIRDAS software will need to be changed (in “change configuration / computer) so the BAIRDAS software recognizes communication is through the 2nd port. 1st port communication is the BAIRDAS default port
Be sure software is setup as follows:
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If, after following the above instructions, or if you have any questions, please contact Tech Support at Antares Analytical for further assistance
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