Step 1
The first step in diagnosing an OPC problem is to determine
if the client application is actually talking to KEPServerEX.
The easiest way do this is to check the status bar of KEPServerEX
and see if the server thinks any OPC client applications are attached
and using tags. Check the Connection Status Bar at the lower right
edge of the KEPServerEX window.
The status bar must display at least one Active Client and one of one
Active tags or the KEPServerEX communication driver in use will not poll
the PLC or device to request data. If the Connection Status Bar is blank,
then no client application is connected to the server and no data
is being requested. This tells you that the problem lies between
the OPC client application and KEPServerEX.
Listed below are some of the more common client/server connection problems:
1. The client application is not in Run mode.
All users should be aware that KEPServerEX will
not attempt to talk to their target device or show
any active tags until they run their OPC client application.
2. The configuration of the KEPServerEX program ID in the
OPC client is incorrect. Check the OPC setup in the OPC
client you are using. The example below shows a screen shot
of the connection properties window of our free OPC Quick Client:
As shown the proper "Prog ID" for KEPServerEX is "Kepware.KEPServerEX.V4".
Case is not important so don't worry if the user enters it as all lower case.
HMI client products may also refer to the Prog ID as the "OPC Server
Name", "Server Name", "Server Address", or "OPC Server".
3. Another possible issue can also be incorrect tag item names.
If you enter bad tag items you may see KEPServerEX report
that it has a client connection but Zero of Zero tags will
be active. Check the KEPServerEX Event window for error
messages.
4. Another possible issue could be DCOM configuration. Under
most circumstances KEPServerEX will install itself and properly
configure its own DCOM settings to work properly with OPC client
applications. DCOM issues form the body of our complete DCOM
configuration document. See DCOM issues Before editing DCOM
perform the alternate test in step 5 below.
5. Another way to test the DCOM settings is to use the OPC
Quick Client provided with KEPServerEX. Invoke the Quick Client
using the tool bar icon on KEPServerEX as shown here by the
arrow:
Once you click on the Quick Client button the Quick Client
will be launched. The Quick Client will then automatically
browse KEPServerEX for any available tags. If this works
correctly then you know the DCOM settings are OK and the
problem may be in the OPC client application.
Contact Kepware Technical Support.
Technical Support Form
Step 2
If you determine that the connection between your OPC client
and KEPServerEX is good then the next most likely problem could be
between KEPServerEX and the device. As shown in the view below
KEPServerEX has reported that the device, in this case a GE9030 PLC
is not responding to communications requests.
If you do not see a "Device not responding" message in the Event window proceed to
Step3 If you see a "Device not responding" message, this means that the driver is
polling the device for data but is not receiving a recognizable response. This is
classified as a communication problem.
If you suspect a communication issue to be the root of the problem here are the most
common causes of communication errors.
1. Cables - The cable used between the PLC and the device is always the first place
to start. The only sure way to confirm the cable is to ensure that you are able to use
this cable with other software such as the device configuration or programming package.
If you confirm that the cable works with your programming package the most likely cause
of the problem will be flow control settings. You may want to try setting the
KEPServerEX channel configuration to a Flow Control of RTS Always or RTS,DTR.
This is a common solution. Each KEPServerEX communications driver includes a specific
help file with connection information and cable diagrams. Driver help can be
accessed from the KEPServerEX Help menu or by going to the desktop start menu,
then Programs folder, and then KEPServerEX folder. When using RS-485 or RS-422,
check the Kepware web site for converters that we recommend. RS-485 and RS-422
converters are a common source of communications issues. If you are using KEPServerEX
Modem capability for dial up modems, be sure to thoroughly read the Modem section of
the KEPServerEX help file.
2. Channel Communication Settings - Do the channel settings for baud rate, parity, and
number of data bits match the current parameters of the PLC or device? A quick test
is to use the ladder-programming package of the PLC to confirm these settings.
The full time online nature of KEPServerEX allows the communication settings to be
adjusted while KEPServerEX has active client connections, so troubleshooting adjustments
can be made quickly and easily. Simply invoke the properties tab on the channel in
question in KEPServerEX and make the adjustments as needed.
3. Device ID - The Device ID set in the KEPServerEX project must match the
communication ID of the PLC or device. Check the specific driver help file for unique
device settings. Like the Channel properties of baud rate and parity, users can change
the Device ID on the fly. Simply invoke the properties dialog for the given device in
KEPServerEX and change the device ID as needed.
For Serial drivers: Most serial devices have a default ID of 1, but you must
check the current ID of the device. You should be able to check this using the ladder
programming package of the PLC. Also, make sure that the IDs in the device and KEPServerEX
are in the same Decimal, HEX, or Octal format. The most common format is Decimal. Device
IDs can also be adjusted while KEPServerEX has active clients.
For Ethernet drivers: Verify that you can ping the PLC's device IP from a
Windows command prompt. If you cannot successfully ping the device, the KEPServerEX
Ethernet driver in use will not be able to communicate with the device.
For Modbus Plus(uses Modicon SA85 card): Verify devices on the Modbus Plus network
with the Modbus Plus Network Browser Utility that installs in the KEPServerEX|Utilities
folder of the desktop start menu.
4. Comm Port - Is the serial communication port (comm port) of the PC valid and not
currently being used by another application or device? Are you certain that the comm
port works? Use some other software package to verify that the comm port is functioning
properly. If extra comm ports have been added to the PC, there could be an issue with
IRQ conflicts. If the comm port is not working, the server will post an error message
to the Event window. Check the "Error Descriptions" section of the appropriate driver
help file for info on comm port error messages.
KEPServerEX does offer some unique built-in diagnostic tools that can make trouble
shooting these types of issues a little easier. To enable the diagnostics invoke the
properties dialog on your channel name in KEPServerEX. Once the properties of the channel
have been exposed click on the "General" Tab. You can enable the Diagnostics as
shown here:
Once the diagnostic features have been enabled invoke the diagnostic view by right
clicking on the channel name and selecting Diagnostics, the result is the display of
the diagnostic window as shown here:
As you can see the diagnostic window provides a protocol view as well as statistics
on the number of read and writes that are occurring and the number that have failed.
One of the most important aspects of the diagnostic window is the protocol view. If
you display the diagnostic window first then invoke the channel properties dialog,
you will be able to make changes to baud rate, parity, or stop bits and see the effect
that has on the success or failure of the communications stream. This can be a powerful
tool for helping you debug your communications issue. We almost go so far as to say it
makes troubleshooting fun. For more information on the diagnostic window consult the
KEPServerEX main help section "Diagnostics".
Contact Kepware Technical Support.
Technical Support Form
Step 3
Not all problems are directly related to a loss of communications. In some cases the
driver can communicate with the device but the device may not like what the driver is
requesting. Additionally the user can also ask the driver to perform an action that it
does not allow. This next section covers some of the most common issues of this type.
If you notice any other relevant warning or error messages displayed in the server Event
window please review the following list of messages for possible causes:
1. Failed to add item - As shown here, KEPServerEX has refused to add a tag because
the user requested something that was outside of the allowable address range.
To remedy the issue, verify that the item reference of channelname.devicename.itemname is correct.
In the example above we show a dynamic reference to a Siemens S5 output address. By checking the
Siemens S5 driver help file (Addressing section) we see:
Discrete Outputs Q0.b - Q127.b.b is Bit Number 0 -7 Boolean Read - Write
Thus for discrete outputs, only bit offsets in the range of 0-7 are allowed, thus
the dynamic reference of "Q0.8" is not valid so the server fails to add the item. This
is a very common mistake.
2. Bad Address in Block (Modbus family of drivers) - Many communications drivers will
report a bad address request when they issue an out of bound command to the PLC.
In this example, the user is referencing holding register offset (denoted by leading 4)
25001 but the address does not exist in the PLC so the driver posts the error message.
Consult the hardware vendor documentation for the PLC or device to determine valid offsets.
Many non-Modicon devices use non-contiguous address references, and you may need to reduce
the holding register block size as shown below:
If the block sizes are grayed out, you will need to disconnect the client application
before you will be able to edit the block sizes.
3. Time comparison error:
After entering a valid license number the server will provide a 10 day grace
period in which to unlock the driver license number.
If the user attempts to roll the clock back on
the PC the server will not allow a new 10-day grace
period.
4. Demo period has expired for 10 day grace period: When the user is issued a
license for a KEPServerEX driver and they enter this
license number into KEPServerEX they are given
10 days to contact Kepware Technical support or use
our online
registration & unlock interface to finish
unlocking their driver.
If the user fails to finish
unlocking their driver within that 10 day period KEPServerEX
will time out on this 10 day grace period and the
driver will cease to run. The user still
has the ability to call Kepware or sign in to their
My Kepware account to receive their unlock codes.
Once the 10 day period has expired
the
driver
will no longer run until the user obtains and enters
the unlock code.
Contact Kepware Technical Support.
Technical Support Form
