Baud rate
The speed at which data is sent through a serial port. It is the number of bits per second sent, but includes stop, start and parity bits which are in addition to the data. The Hiden interface units communicate at a fixed rate of 19200 baud ( 19.2 kbaud ). This corresponds to a maximum rate of 1920 bytes of data per second.
COM port, Comm port
Communications port. A PC normally has up to 4 serial COM ports, COM1:, COM2:, COM3: and COM4:
Conflict
If two pieces of hardware are assigned the same I/O address then they will both respond when only one of them should.
This is an I/O address conflict.
If two pieces of hardware are assigned the same interrupt then the processor will not know which one has signalled it when the interrupt occurs.
This is an interrupt conflict.
These situations are known collectively as resource conflicts.
FIFO
First In First Out.
The 16550 UART contains a 16 character FIFO buffer that allows it to store characters while it is waiting for the PC to respond.
Interrupt
An interrupt is a signal that hardware on the PC uses to signal to software that something has happened. The PC responds by running a routine called an interrupt handler.
A PC only has 16 interrupts request lines ( IRQs ), most of which are already used
I/O address
Input Output address
Hardware on the PC is connected to the processor by a set of signals known as the address bus. A unique combination of signals for each piece of hardware allows the processor to select each one individually. This combination is known as the I/O address.
IRQ
Interrupt ReQuest.
The electrical signal that causes the processor to generate an interrupt. The PC only has 16 IRQ lines.
Overrun
When the UART receives another character before the interrupt handler has processed the last, or, on UARTs with a FIFO, before it has emptied the FIFO when the FIFO is full
Usually caused by another piece of software disabling interrupts for too long.
The most common COM port problem..
Resources
Anything which a computer has a limited amount of: Memory, interrupts, I/O addresses.
RS232
The electrical standard for the serial port connector. Properly only applied to 25 way connectors.
Serial
One bit after another, as opposed to parallel, simultaneously side by side.
Serial port
A communications port through which serial data is sent.Effectively synonymous with COM port
UART
Universal Asynchronous Receiver / Transmitter.
The device that converts characters from bytes to a serial stream of bits and vice-versa.
Serial communication used to be the simplest way to communicate with a PC. The complexity of modern PCs has lead to interactions between software and hardware that makes it more likely that there will be problems. The following attempts to explain why this is so.
MASsoft and ESPsoft communicate with their Interface Units either through a serial port or over a network. The software running on the PC sends a command to the interface unit as a sequence of characters, and the interface returns a reply. For instance, to find out if the emission is OK, MASsoft sends the command lget emission to the MSIU. The MSIU responds with 1 if the emission is OK, or 0 if it is not.
When communicating through the serial port you use the Communications Configuration utility in the Hiden Applications group to select which COM port you wish to use. PCs and notebooks can have up to four COM ports, but not all of them may be free for use.
Sometimes your mouse may be connected to a COM port. If possible use a PS/2 or. USB mouse.
Your Modem may be connected to one of the COM ports. Even if your Modem is internal or built in to your PC it usually appears to software as if it were a COM port.; the PC will send output for that COM port to the modem.
If you have an IRDA ( InfraRed or IR ) port then this will usually take the place of one of the serial ports
If you do not have a spare port you could install an additional serial port card, either ISA, PCI or PCMCIA, that contains one or two or more additional ports Multiport cards may come with special Windows device driver software. Multiport cards may have a larger FIFO than the stadard 16550 or may be “intelligent” devices with their own microprocessor; such cards may help overcome overrun problems. However even simple two port cards are often more expensive than a network card, and, as we will see, having more than two ports is not as helpful as it might seem.
When MASsoft starts up it “opens” the serial port that you specified in the Communications Configuration Utility. By “open” we mean that it tells Windows that it wants exclusive use of the port. If any other program is using the port then MASsoft will not be able to open the port. Therefore you must make sure that any other software that uses the serial port is closed before running MASsoft. This may be communications programs like HyperTerm ( or Hiden’s version of TTY ), software for other scientific equipment, Programs with Telephony ( TAPI ) support ( e.g. mail list with dial-out facilities e.g. Cardfile ), software for synchronising with laptops or for remote control ( e.g.. Laplink ), Palm device software ( e.g. 3COM’s Palm Desktop ) etc.
If MASsoft can not open the serial port the Mass Spectrometer will be “Unavailable”.
When ESPsoft is started if it can not open the serial port the “looking for” dialogue will say “Unavailable” instead of “Found”.
When MASsoft first connects to the MSIU it sends a command to get the name of the instrument and its firmware revision level. If it does not already “know” the instrument, or if its firmware has been changed, MASsoft “interrogates” the MSIU.
During interrogation, MASsoft sends commands to the MSIU to get the names of all the devices ( DACs, inputs, outputs, etc. ), then gets information about each device ( minimum and maximum values, units, etc. ). If a communication error occurs during this procedure the interrogation can become corrupted. This will result in “Unknown logical device” errors later.
If corruption occurs later, when data is being transfered from the MSIU to the PC, then you may get “Results data corrupted” errors, or more likely just a “Comm port error” dialogue being displayed, followed by the loss of the link to the MSIU.
The most common cause of corruption is an overrun error; this occurs when the PC receives characters faster than it can process them. The interface units communicate at a fixed baud rate of 19.2K baud, that is 1920 characters per second maximum, or one character every 500 _s. With the typical modern PC running at atleast 300MHz this is enough time for 15000 instructions at 10 clock cycles per instruction. To see why even this is not enough we need to go into a bit more detail:
MASsoft ( or ESPsoft ) is continuously sending commands to the MSIU and then receiving replies. This is what happens when it does this. MASsoft generates the command and passes it as a sequence of characters to the operating system ( Windows ). Windows takes the first character and sends it to an I/O address that connects to the UART. The UART gets the character and writes it into the FIFO, it then starts to send the character ( which consists of 8 “bits” ) one bit at a time as series of positive and negative voltages down the RS232 cable. Meanwhile, Windows reads an I/O address to check that the FIFO is not full, and, if it is not, it writes the next character. If the FIFO is full Windows does something else while it waits. Windows now needs to be told when there is space in the FIFO. This is done by an Interrupt. An Interrupt is a signal between the hardware and the software. When the Interrupt occurs Windows starts to write characters to the FIFO again; this repeats until the command has been sent.
The MSIU receives the command and sends a reply.
The PC’s UART receives the reply , and as each character is received, it writes it to another FIFO. When the FIFO is three quarters full an interrupt is generated. When the PC handles the interrupt it reads an I/O address to fetch a character from the FIFO. It does this until the FIFO is empty.
If the PC does not handle the interrupt then the FIFO will fill up; if a character is received when the FIFO is full it will be lost. This is an overrun error.
Why might the PC fail to handle the Interrupt?
- The obvious answer is because it is busy. Interrupts are called Interrupts because they tell the computer to interrupt what it is doing and do something more important or urgent:
- If the computer is already doing something more important than reading the serial port ,then the serial port Interrupt will have to wait until it is finished.
- If the computer is reading the serial port when another, more important, Interrupt occurs then the serial port Interrupt will itself be interrupted.
- There are times when it is dangerous for the computer to be interrupted, if the computer must finish what it is doing it can “disable” the Interrupts until it is safe to do so.
If any of these take more than 2 ms then the FIFO can go from three quarters full to overflowing, and a character is lost.
Another problem arises because PCs originally only had 8 interrupts. Modern PCs have 16, but standard serial devices can only use the first 8, most of which are used by the PCs motherboard, therefore COM1 and COM3 share IRQ4 and COM2 and COM4 share IRQ3
If you share an interrupt the software has to work out where the interrupt really came from, which slows it down. This problem is most likely to arise if you have the Mass Spectrometer connected to COM1 and a modem on COM3 ( or on COM2 and COM4 respectively) or if you try to run another peice of scientific equipment ( e.g. a grating or collimator ) from another port.
This is also why you can not have a mouse connected to COM1 and use COM3 ( or vice versa ) or a mouse on COM2 and use COM4 ( or vice versa ). The mouse software can not share an interrupt with the serial port software.
16 IRQs is not really enough which leads to the possibility of two devices being assigned the same interrupt request number ( IRQ ). If the two devices assigned the IRQ are not capable of sharing this leads to an “IRQ conflict”
This shortage of IRQs is why having more than two serial ports may not be helpful.
The following was obtained by selecting System in the Control Panel. Select the Device Manager tab and click on Computer at the top of the device tree. Click on properties to view the resources:
As you can see there are no free interrupts. IRQs 5, 9, 10 and 11 are used twice.
IRQ2 is daisy chained to IRQ9.
PCI devices can share IRQs by using IRQ Steering. If the BIOS is not fully compliant, this option may lead to machines not shutting down properly even if 2 or more devices are not sharing an IRQ.
PCI bus IRQ Steering can be disabled in the PCI bus device in System Devices in the Device Manager in System in the Control Panel.
You can also use this dialogue to check for I/O address conflicts. Every device must have a unique I/O address. If two devices have an address conflict it is likely that neither device will work.
For futher information, if you can get a copy, I recommend a file that is shipped with the Palm Pilot called Comport.txt. You could also read the MODEM section of FAQ.TXT which you will find in your Windows folder.
Step 1 : Basic Terminal Test
Connect the serial cable to the MSIU. Ensure that you connect to the
RS232 connector not the RS422.RS485 connector.
The connectors are arranged like this on the back panel:
(RS232) (RS422) (NET)
DO NOT CONNECT TO THE MIDDLE CONNECTOR!
Start Terminal from the Hiden Applications group ( HAL4.HT).
Switch on the MSIU. The cursor on the Terminal screen may shift 1 space
to the right and the MSIU should beep once.
If the cursor keeps shifting to the right this indicates that the MSIU is continuously re-booting.
Type in HELP. A summary of MSIU commands should be displayed.
If this step succeeds procede to Step 2, if not go to Step 3
Step 2. TTY Test
This step tests the communications between the MSIU and the PC by sending a message back and forth and checking for errors.
To run TTY select Run... in the Start Menu. Click on Browse and navigate to \Program Files\Hiden Analytical\Common. Double click on the TTY Icon.
When TTY has loaded use Action Connect to connect to the MSIU. Type in the command HELP, the help text should be displayed.
Click on Settings in the menu bar. The Settings dialogue is displayed..
In the Settings menu dialogue box check the Echo Back check box in the TTY Options box then click on OK
Type the command TEST ASCII
The MSIU should return the command TEST ASCII followed by a cycle count and a string of letters. These should continue to scroll up the screen until you clear the Echo back check box.
If you get *C001* repeating it means that you have typed the command "TEST ASCII" incorrectly. The MSIU sends the error *C001* to TTY.EXE, TTY.EXE sends *C001* back to the MSIU. *C001* is not a valid command so the MSIU sends *C001* back again... To get out of this cycle clear the Echo Back check box in the Settings Dialogue and click on OK. Press return in the TTY window. Then turn Echo Back on again and try again.
This test will test the communication between your PC and MASsoft by sending the message back and forth, checking that no characters are lost or currupted, until stopped. If an error occurs the test stops automatically; please note the cycle number. This test is independant of the version of MASsoft.
If there is an error you will get a line that begins : “ASCII mismatch in cycle” ...
Examine the last line carefully for an error code. The error code takes the form <CExx> where xx is a number, hidden in the received text string.
The most common error number is 2. This an overrun error. This indicates that your PC is unable to receive characters as fast as the MSIU can send them. See section “”.
If there is no error code then the most likely cause is that a character has become corrupted. Examine the response for a modified character. This is a problem with the electrical transmission of the RS232 signal. Possible causes:
•Poor/disconnected screening of the RS232 cable.
•The RS232 cable is too long
•The PC or MSIU are not connected to a common earth ( ground ).
•The PC and MSIU are on different phases of a 3 phase supply.
•The electrical environment is too noisy.
If the TTY test will not run for tens of thousands of cycles without error then MASsoft will fail.
Step 3 Test the PC serial port
If Terminal fails to communicate with the MSIU then you need to check if the serial port on the PC is functioning.
The easiest way to do this is to link COM1: on the MASsoft PC to another PC’s comms port, and run Terminal on both computers. When both ends are set to the same serial link parameters, you should be able to type into one PC and see the results on the screen of the other, and vice-versa.
Alternatively check that the comm port is working properly by plugging the serial
cable into COM1: and looping the signal back.
Disconnect the cable from the MSIU and link pins 2 & 3 at the MSIU end ( a bent paper clip is good for this! ). This connects transmit to receive .
The pins are numbered
-------------
\ 5 4 3 2 1 /
\ 9 8 7 6 /
---------
Start Terminal from the Hiden Applications group ( HAL4.TRM). Type in ABCD,
AABBCCDD should be displayed on the screen.
Remove the link and type ABCD, you should see just ABCD.
Note: There is a bug in the version of HyperTerm shipped with Windows 98; it fails to echo back the characters typed. Therefore you will see ABCD in the first case and nothing at all with the link removed.
Step 4 Test Comms from DOS
If you suspect a problem with Windows use a DOS terminal emulator such as DATATALK, CROSSTALK or PROCOMM running on the PC. The terminal emulator may over-ride the baud rate set in the AUTOEXEC.BAT file, so you will need to check the settings used in the emulators own menus.
When communicating by Terminal or from a DOS program ensure that the link parameters of the PC are the same speed as the MSIU. The baud rate, number of data bits, number of stop bits and parity used must be matched. These may be being set by a command in the host software or by a 'mode' command in the PC's AUTOEXEC.BAT file (refer to your DOS manual for details). The MSIU is fixed at 19200 baud, 8 data bits, 1 stop bit and parity off. If necessary the following line can be put in the PC's AUTOEXEC.BAT file to configure COM1:
MODE COM1:19200,N,8,1
When using Windows Terminal the comms parameters are set in the Settings Communications dialogue. If you have started Terminal from the Hiden applications group, this will automatically load the HAL4.TRM file which sets the correct parameters for communication.
If the comms paramters are wrong, you may find that you get random characters instead of the correct response when you send commands to the MSIU. Start Terminal first and then switch the MSIU on. Type AAAA followed by carriage return, you should get *C003* back. Type A followed by carriage return and you should get *C001* back.
. By default MASsoft uses COM1: to link to the MSIU. Ensure that the cable to the MSIU is connected to COM1: on the PC. If you are using COM2: use the Comms configuration utility in the Hiden Applications group to change the comms port.
. In Windows for Workgroups 3.11 MASsoft crashes while interrogating the mass spectrometer or as soon as it starts to down-load a scan and displays a message box such as:-
*C001* Command Error 1 "Unknown Command"
*C003* Command Error 3 "Command Truncated"
There may be a problem with the version of COMMS.DRV used by Windows. The RS232 driver supplied with Windows for Workgroups 3.11 and Windows 95 has been found to cause problems when used with MASsoft as it generates a spurious character in the receive buffer when the comms port is opened. (See also the note about Gateway Colorbook2 RS232 link below).
edit the SYSTEM.INI file in the Windows folder. Find the line
comm=comm.drv
and change it to be
comm=PATH\comm.drv
where PATH is the path to the hiden common folder (normally c:\Program Files\Hiden Analytical\Common. This should be entererd as C:\PROGRA~1\HIDENA~1\COMMON ).
NOTE this problem is fixed within MASsoft itself in the current version. only one program can use COM1: at a time. Exit Terminal and any other program that might use COM1: before running MASsoft. Ensure that no programs are started in the StartUp program group that use COM1:.
. is the cable connected the right way round? The two ends of the early versions of the Hiden RS232 cable are different. If you cable is not labelled HA-061-014/b, where /b is the revision letter, ( or any later revision ) then you must ensure that the end labelled PC is connected to the COM1: port of the PC and the other labelled HAL 4, HAL IV or HAL RC connected to O7 RS232 on the MSIU.
. if you have bought or made up your own cable is the cable wired correctly? The cable provided by Hiden is not standard, each end is different, and it is easy to make a mistake in connecting up the RS232 cable. It is vital to ensure that the transmitted output from the MSIU is connected to the receive input of the PC, and vice versa. Some cables swap these over, some do not, and you may need to use a null-modem to swap them over. See see your MASsoft manual for a drawing of the cable connections. Note that the PC's DSR & CTS signals must be connected to the MSIU's RTS signal. A suitable cable is available from Hiden.
. check the cable and baud rate by using a terminal emulator such as the Terminal program provided in the Hiden group. If you use this version of Terminal, it will be configured automatically with the correct parameters to talk to the MSIU. If you use the version in the Windows Accessories group, you will need to set the parameters manually. You must use 19200 baud, 8 data bits, 1 stop bit, parity off
. is the cable too long? The maximum recommended length is 10m, less in an electrically noisy environment. If a longer length is required use the Ethernet LAN.
. is the MSIU connected to the same phase of the mains as the PC? It is common in industrial premises for the supply to be derived from two phases of a three phase mains, and even adjacent benches may be on different phases. If two pieces of equipment are powered by different phases the noise on each adds across the RS232 link, and may cause transmission failure. If a phase difference is unavoidable use the Ethernet LAN or some sort of RS232 isolator.
. are both the PC and MSIU securely earthed (grounded)? If the PC and MSIU do not share a common earth (ground) then a voltage difference may exist which could upset the RS232 voltage levels. If in doubt use the Ethernet.
. is the electrical environment noisy? Does the RS232 cable run parallel to cables carrying heavy currents (especially if switched) or close to machines generating magnetic fields? Avoid running the RS232 cable in the same duct as power cables or alarm bell circuitry.
. don't try to connect the MSIU to the PC's printer port (a 25 pin D socket) via a gender changer by mistake.
. if you have a serial mouse it can be used in COM2: and the MSIU connected to COM1:
If you use the mouse in COM1: then you must use the Comms configuration utility in the Hiden Applications group to change the comms port to COM2:
Check that another application has not installed incompatible driver files. Make sure that the sizes and dates of the files Comm.drv and Serial.vxd in the System folder are the same as the original versions on the Windows CD
. Confirm that the following lines are present in the System.ini file:
[boot]
Comm.drv=Comm.drv
[386enh]
device=*vcd
. Check the UART type and FIFO buffering
The Universal Asynchronous Receiver Transmitter ( UART ) is used by the PC to convert the serial RS232 signal to 8 bit characters.
MASsoft and ESPsoft communicate at a speed of 19.2K baud. This rate is not alterable. At this speed computers with 8250 or 16450 UARTs will miss characters.
You must have a computer with at least a 16550 UART, which has a 16 character “First In First Out “ ( FIFO ) buffer.
The FIFO must be enabled. You can change the FIFO settings in the Control Panel
In the Control Panel double-click on System. Select the Device Manager tab and find Ports in the tree. Click on + to expand the level then select a Com port,
Press the Properties button ( or click on the port with the right hand mouse button select and Properties from the pop up menu ).
Select the Port Settings tab. This displays baud rate settings for the Com port - these settings have absolutely no affect on MASsoft, ESPsoft or HyperTerm!
Click on the Advanced button.The Advanced Port Setting dialogue is displayed:
Ensure that “Use FIFO buffers” check box is ticked.
The Receive Buffer setting should be set as above.
With a 16 character buffer this setting will generate an interrupt when 12 characters have been received, leaving room for 4 more. If more than 4 characters are received before the interrupt is handled they will be lost.
However if the receive buffer setting is lowered to its lowest setting then there will be room for 12 characters before the buffer overflows, but 3X as many interrupts will be generated, putting a heavier load on the processor.
.There is an entry in System.ini COM1fifo=0, this indicates that FIFO buffering in the 16550 UART is disabled. This should be re-enabled:
Go to the control panel. Select System. The System Properties dialogue is displayed. Choose the Device Manager tab. Find Ports (COM & LPT). Click on + to expand the tree. Select Communications Port 1 (COM1).
The Communications Port (COM1) Properties dialogue is displayed.
Select the Port Setting tab. Click on the Advanced... button.
Make sure that the Use FIFO buffers (requires 16550 compatible UART) check box is selected. Adjust sliders for faster performance.
Ok all the dialogue boxes and reboot. Check that the COM1fifo= entry in SYSTEM.INI has changed to 1 after rebooting. If not then delete the line and reboot again.
. under Windows, COM1: is interrupt driven. If another device is configured to use the same interrupt, Windows may miss characters. Don't configure any other devices (e.g. network cards ) to use COM1:'s IRQ (COM1: usually uses IRQ4, COM2: IRQ3).
If another device uses the same interrupt or input/output ( I/O ) address it is said to “conflict”. You can check for conflicting devices in the Control Panel:
In the Control Panel double-click on System. Select the Device Manager tab and find Ports in the tree. Click on + to expand the level then select a Com port,
Press the Properties button ( or click on the port with the right hand mouse button select and Properties from the pop up menu ).
Select the Resources tab to display the current resources for that port.
The “Use automatic settings” check box should normally be ticked.
COM1 is normally on IRQ4 and uses an I/O address range of 03F8 to 03FF.
COM2 is normally on IRQ3 and uses an I/O address range of 02F8 to 02FF
Below this is the “Conflicting devices” list. This should say “No conflicts”.
If any devices conflict then that device should be found in the Device Manager tree and its resources changed so that they do not conflict with the COM port. It is not recommended that the COM port be changed from the standard settings unless unavoidable ( i.e. if the conflicting devices interrupt or address can not be changed ).
Also, some display adapters have an address conflict with COM4 ports ( Diamond Stealth S3 and STB ). To work around this conflict, use another COM port or replace your graphics adapters.
. disable any power saving features that might power down the comms port. This is most likely to be a possible problem on Notebooks but some Energy Star compliant desktop PCs have these features too. You will probably have to invoke the BIOS setup program to do this - refer to your PC manufacturers hardware manuals.. Virus checkers can use up a lot of your computing power. While scanning files your PC may be too busy and miss incoming characters on the serial port. Try disabling the virus checker and see if the problem is solved. You may need to do scheduled scans at times when the Hiden Software is not in use and to disable background virus checking. It is, however, important that your PC is regularly scanned for viruses.
. Screen savers are another possible source of problems. Disable your screen saver.
. Some DOS programs can interfere with the use of the serial port. To prevent a DOS program taking control of the serial port while a Windows program is using it under Windows 3.1 and WFW 3.11 go to the Control Panel and choose the 386 Enhanced Icon. Select the serial port used by the Hiden application ( usually COM1: ). In the device contention group select Always Warn. You will then get a dialogue box displayed if a DOS program tries to grab use of a COM port.
. Cardfile has an auto-dial function which allows it to dial a telephone number if a modem is connected to the serial port. If Cardfile is started while MASsoft or ESPsoft are running it will grab use of the serial port from them.. MODEMs. Modems are usually assigned to a COM port, even on board or internal modems. If your modem is assigned to COM3 it may share an interrupt with COM1. If you do not use the modem then disable or remove it. If you do use the modem then assign it its own IRQ. If this is not possible then assign the modem to COM4 ( assuming the Hiden equipment is connected to COM1 ) or connect the Hiden equipment to COM2 .
. IrDA or FIR ( InfraRed ) ports. On some new PCs and notebooks one of the COM ports, usually COM2, is assigned to the IR port. You will need to disable the IR port . This may be a BIOS setting or a jumper on the mother board.
IBM ThinkPad owners should use the “ThinkPad Features” program to disable the IR port and enable Serial Port COM 1; then re-boot your notebook.
. Serial to USB converters. To the best of our current knowledge no serial to USB converter, or USB hub with a serial port, will work with Hiden software.
. Using other scientific equipment connected to another serial port may cause errors . This is particularly true if you have more than 2 serial ports - see next point.
. if you have 4 serial ports, COM1 to COM4, then COM1 and COM3 share interrupt IRQ4 and COM2 and COM4 share IRQ3. The result of this is if the MSIU is connected to COM1 then using COM3 may cause COM1 to miss characters. Likewise COM2 and COM4.
. You can not connect a mouse to COM1 and use COM3, or vice versa. Likewise you can not connect a mouse to COM2 and use COM4. This is because the mouse and a COM port can not share an interrupt, see above. Note: You can not use a mouse on COM3 or COM4, see Microsoft Knowledge Base: PSS ID Number: Q72394.
. If you have an unused network card with a BNC connector make sure the connector is terminated with a T piece and two 50 ohm terminators.
. If you have a program that monitors your CPU temperature on your task bar try disabling it. You may be able to configure it by left clicking on it or perhaps right clicking on it and selecting properties, or possibly through the control panel
If the computer is a Compaq then disable the CPQAlert program that monitors the CPU temperature. Remove from registry:
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\RunServices
or NT equivalent.. Check that the PC is not running too hot - this tends to be a problem with notebooks. Check that your fan and CPU fan are working. If it runs for 45-60 minutes when you switch on then fails, then only for 20 minutes if you re-boot and perhaps a bit longer if you switch it off for 10 minutes it points to temperature being a problem.
. the instrument name may have changed. The new EPROM configuration program may have an extra space between the name and the works reference number, immediately before the #. When MASsoft starts up it opens the comms port and asks the MSIU to send back its ID, it compares the reply with the MSIUs that it knows about and sets the correct MSIU active. If the ID changes, even by 1 space, MASsoft does not recognise the MSIU. If you do System Explore you may find that you have 2 mass-Spectrometers in the MassSpecs menu with identical names, apart from 1 space. One of these will be Available, the other Unavailable. The fix for this is to reinterrogate.. 3COM Etherlink 3C509 Parallel Tasking network cards disable the interrupts for a long period of time. The maximum time is determined by the Modem baud rate parameter. The modem speed should be set to 19.200. Use 3Com's diagnostic utility.
See Microsoft Knowledge Base article ID: Q96948 “WFWG: 3C509 Modem Setting May Disable Network Functionality”
