Ethernet connectivity Problems


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I am currently having trouble reading modbus registers from an E-senza wireless gateway device.

I have previously communicated with the device with no problems using both the quickmod programme and using communication devices within my own DF setup.

As of now I can read the modbus registers through the software provided by e-senza and also through running "modpoll" under the Run cmd function.

IP address of the device match that of the LAN and port 502 is being used for modbus communication.

It has been suggested that perhaps the device needs to be read in complete blocks. In the case of this E-senza device, blocks of 20. Hence possibly why the following modpoll command will work and yet under the same settings within DF, the holding registers are unobtainable.

".\modpoll.exe -m tcp -r 40021 -c 20 -t 4"

Is there a command within DF to read modbus registers in blocks? Or perhaps you could offer some other troubleshooting diagnostic tips to try and resolve the problem.

I believe Matt has been in touch with Gavin Chalkley from Amplicon who we purchased DF from if he may be able to shed any more light.

Many thanks for any assistance.


Mark Ellis

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You can quickly find out if you need to read all 20 by calling modpoll with -c 10 or something and see if it fails. Anyhow, you can have DF read in blocks using three different ways:

1) in quickMod (which I recommend only in the beginning), just specify the count of 20 and it'll read 20 registers

2) once you are creating your own document, you can simply create 20 channels with consecutive modbus addresses.

3) you can also do it in script using something like: device.mydevice.readHoldingS16(4, 40021, 20)

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OK, Thanks for that, we seem to have solved our problems without quite finding out what the route cause was, but just one more quick question.

I have deleted a comms device from my prgramme, and subsequently it has disappeared from the device list in the channel listings and is not available to configure. However, if you right click in the comms monitor box; you can still select to monitor it. How can I completely remove it from my programme, as I believe it to be the source of most of my socket errors??



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There is a difference between a comm device and the port. This is to allow you to put two different devices on the same port (handy when using radio modems and the like). The monitor window refers to the port, not the device. Deleting the device doesn't delete the port. To delete the port, go to New Serial / Ethernet, click the port, and hit the delete button above the list.

Note you can also remove socket errors from disconnected ports that you don't want to delete by setting the address to a blank string. For serial ports, set the port # to 0.

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