Data Station Modbus TCP/IP issues

Hi All, I have an issue with a Red Lion Data Station (Crimson 3.0 V707). The Data Station is set up as a Modbus Master TCP/IP and is connected to a Burner Management System and a CompactLogix (RSLogix 5000 V20). The system has been reading the Modbus registers in the Burner System and relaying them to the CompactLogix for about 5 days. Today the Burner Technician disconnected his programming laptop from the Burner System and reconnected the proprietary HMI screen. This is when the Data Station could no longer read the Modbus registers in the Burner system. The Data Station "DeviceOnLine()" shows the connection to the Burner System as healthy, and the only time the Modbus registers are updated in the Data Station is when the "Watch Table" is active and then it is only the registers in the active watch table. I have cycled the power on the Data Station with no effect, but cannot cycle the power at the Burner end.

Has anybody had a similar situation or any thoughts on what the cause may be?
Thanks
Woolie

woolie161 said:

Hi All, I have an issue with a Red Lion Data Station (Crimson 3.0 V707). The Data Station is set up as a Modbus Master TCP/IP and is connected to a Burner Management System and a CompactLogix (RSLogix 5000 V20). The system has been reading the Modbus registers in the Burner System and relaying them to the CompactLogix for about 5 days. Today the Burner Technician disconnected his programming laptop from the Burner System and reconnected the proprietary HMI screen. This is when the Data Station could no longer read the Modbus registers in the Burner system. The Data Station "DeviceOnLine()" shows the connection to the Burner System as healthy, and the only time the Modbus registers are updated in the Data Station is when the "Watch Table" is active and then it is only the registers in the active watch table. I have cycled the power on the Data Station with no effect, but cannot cycle the power at the Burner end.

Has anybody had a similar situation or any thoughts on what the cause may be?
Thanks
Woolie

Click to expand...

The Data Station will only update values when there is something in the Data Station that is using them. In the case of HMI, that is when the values are on the screen, used for data storage, or alarming. That is why it works when the watch window is open.

A Data Station, it is typically used as a Gateway between protocols. Is that how you are using it? If so, it may be that the Client requesting the data from the Data Station isn't quite set up right.

If you want to post your configuration from the Data Station, we might be able to see the issue (if it is something else)

Data Station Modbus TCP/IP Issues

Thanks for the reply JHarbin, Yes the Data Station is being used as a Protocol converter being Modbus (TCP/IP) at the Burner System to a Allen Bradley CompactLogix PLC. The Tags in the PLC were continuously being updated with the values from the Burner system until recently. In layman's terms, it appears as though the data station isn't polling the slave. I have attached the crimson 3 file.

Thanks again for your interest
Woolie

RedLion "GetDeviceStatus() number code

Further to the above, the "IsDeviceOnline() = 1 and GetDeviceStatus() = 257.
Does anybody know the what the Device Status Numbers mean? This may help with unraveling my issue.
Thank you
Woolie

I didn't see your configuration. try attaching it again - I think you have to zip it.

I think your GetDeviceStatus() value means that it is communicating - however it doesn't necessarily mean that it is communicating correctly.

The meaning of the GetDeviceStatus() return value is explained in the reference manual.

257 dec = 100000001 bin = 101 hex

So I would take this to mean that "the device comms is operating correctly" and "some level of response has been received from the device".

Thanks John for the Code Table.

I have attempted to attach the Crimson 3.0 V707 file again

Woolie

woolie161 said:

Thanks John for the Code Table.

I have attempted to attach the Crimson 3.0 V707 file again

Woolie

Click to expand...

I'm having a bit of trouble following your configuration. Why is everything from the A-B PLC being pulled as bits and then sent to Coils in the Modbus TCP PLC. Shouldn't some of them be holding registers?

Maybe a quick description of what you are trying to accomplish would help.

I have cut my Red Lion Data Station program down to 1 Modbus Slave and 1 Register within that slave. While the Data Station "Watch Window" is active on the Modbus register, the PLC tag real the real time value. When the watch window is closed, the PLC tag is no longer updated with real time values.
Woolie

Hello JHarbin,
The burner system Modbus registers are all Integers and if I have tried to read them as holding registers with no success. Reading them as coils worked. Even the burner manual addresses the registers as individual bits. The communications have been working for 5 days straight with no interruptions until yesterday.

The burner management system is stand alone gas burner control. I am trying to pick up the burner status, like "firing rate (integer)" Status (Individual bits) etc. It is only reading the registers, no control (writing) to registers in the burner system.
Woolie

Try adding a comms delay to the device settings (last settings on the pane when you have the device selected under the protocol). Some Modbus slaves cannot handle the rapid fire polling that the Red Lion hardware will hit it with by default.

I have also run across one device that could only handle a request for up to 8 words at a time, so I had to reduce the Frame Register limits.

Disabling spanning reads is another setting that has helped me with a different driver type when dealing with a device that was balking.

EDIT: Looking at your file, I see you have "Ignore Read Exceptions" set to "Yes". That means when there is a read error, you will get zeros for the requested data, and that might be the right choice for your application. With it set to "No" (default), I believe you will get stale data, (assuming that you have read the data at least once) but I am not 100% sure of that, since I rarely use gateway blocks and have not needed to enable that setting. Any application I have that is having comms issues will show the "----" on HMI page indicators signifying an absence of data, but I am not certain of what that means for gateway blocks.

woolie161 said:

Hello JHarbin,
The burner system Modbus registers are all Integers and if I have tried to read them as holding registers with no success. Reading them as coils worked. Even the burner manual addresses the registers as individual bits. The communications have been working for 5 days straight with no interruptions until yesterday.

The burner management system is stand alone gas burner control. I am trying to pick up the burner status, like "firing rate (integer)" Status (Individual bits) etc. It is only reading the registers, no control (writing) to registers in the burner system.
Woolie

Click to expand...

You didn't say what brand BMS it is, but we have read integers from both Fireye and Honeywell BMS units. I know that there are others, but haven't worked with them.

I wonder if they are input registers rather than holding registers. Do you have a link to the manual showing the registers?

Don't take this the wrong way, but you have made a common mistake on the BMS side. You don't need to set up gateway blocks to read out of the BMS, you just need to read the registers directly as tags and then assign the tags to the PLC gateway blocks. Add the BMS as a device under a Modbus Master protocol with the correct comms settings. You don't need anything else on the comms side. Then go to data tags and create an Integer Tag with the BMS and the appropriate register as the source. Then you can send (or make available) that tag to the PLC through the PLC's gateway blocks.

In other words, you set up a Modbus Master to read a tag out of the BMS and then assign the tag to the PLC gateway blocks.

That said, if it *was* working, then I don't think that the PLC is polling the BMS. As I mentioned earlier, that is the only way the DSPLE will actually make requests. That's why using the Watch Window works.

I'd really like to see the modbus map for the BMS if you have a link.

I won't take anything the wrong way as any help is appreciated. Initially the code was done for a G310 screen and the idea was to display the status bits on the screen, hence all the tags that were created for the AB PLC. As for the the comments from OkiePC, I have tried with spanning read disabled and different time delays on the Slave and the PLC. Ignore Read Exception is set to yes otherwise comms is not possible. I have attached a link to the burner manual, but you need to log in to see it. I can send a ".pdf" (12Mb) if required.

https://www.lamtec.de/en/downloads/...]=1286&cHash=872c606c158f60f38268ab57387a2d6d

Thanks
Woolie

woolie161 said:

I won't take anything the wrong way as any help is appreciated. Initially the code was done for a G310 screen and the idea was to display the status bits on the screen, hence all the tags that were created for the AB PLC. As for the the comments from OkiePC, I have tried with spanning read disabled and different time delays on the Slave and the PLC. Ignore Read Exception is set to yes otherwise comms is not possible. I have attached a link to the burner manual, but you need to log in to see it. I can send a ".pdf" (12Mb) if required.

https://www.lamtec.de/en/downloads/...]=1286&cHash=872c606c158f60f38268ab57387a2d6d

Thanks
Woolie

Click to expand...

I could download from the site, but I don't know which manual has the modbus registers (or even which BMS you have)...

From JHarbin:
That said, if it *was* working, then I don't think that the PLC is polling the BMS. As I mentioned earlier, that is the only way the DSPLE will actually make requests. That's why using the Watch Window works.

The data from the PLC tags connected to the data station are MOVEd into a different PLC tag on an unconditional rung. The PLC Heartbeat and the Slave "IsDeviceOnline & DeviceStatus" are working so I assume the PLC is polling the Redlion Data Station.

Woolie