RevolutionPi Connect 5 Modbus RTU Server connection fails

[user]

Hello,

Current setup & problem description

currently I am using a RevolutionPi Connect 5 which is configured as Modbus RTD Server (see: https://revolutionpi.com/de/tutorial/modbus-rtu-server). The Modbus is connected to a Siemens QSA2700D.

The Action Status 1 and 2 returns 255 0xFF.

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ls -l /dev/ttyAMA*

returns

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crw-rw---- 1 root dialout 204, 64 Aug 26 10:21 /dev/ttyAMA0
crw-rw---- 1 root dialout 204, 74 Aug 26 10:21 /dev/ttyAMA10

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ls -l /dev/ttyRS485*

returns

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lrwxrwxrwx 1 root root 7 Aug 26 12:15 /dev/ttyRS485-0 -> ttyAMA4

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cat /etc/revpi/image-release

returns

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BUILD_ID="2026-07-27"
IMAGE_ID="revpi13.0-trixie-arm64-default"
IMAGE_VERSION="13.0"

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ls -l /lib/udev/rules.d/50-revpi.rules

returns

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-rw-r--r-- 1 root root 5332 Jul  1 08:17 /lib/udev/rules.d/50-revpi.rules

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md5sum /lib/udev/rules.d/50-revpi.rules

returns

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4d2f86bf8e73f69b37a1b881c40a38be  /lib/udev/rules.d/50-revpi.rules

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piTest -r Modbus_Master_Status

returns repeatedly

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1 Byte-Value of Modbus_Master_Status: 255 dez (=ff hex)

Solution attempts

• Changed device_path from the default value of "/dev/ttyRS485" to "/dev/ttyRS485-0" and rebooted.
• Tried to apply the solution mentioned here: viewtopic.php?t=4787

I can rule out a broken QSA2700D and false wiring. The same setup works flawlessy on a revpi connect 4 running buster.

Is there anything else that could cause these issues?

[RevPiModIO]

Hi!

An update from pictory and revpi-modbus will be released in the next few hours. These updates must be installed and the PiCtory configuration must be recreated.

Sven

[RevPiModIO]

The update is published. Please update according to the instructions and be sure to create a new PiCtory configuration!

Update: https://revolutionpi.com/en/docs/updates

Sven

[user]

I updated the packages.

I checked the devices list with

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ls -la /dev

which still does not show

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/dev/ttyRS485

but only

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/dev/ttyRS485-0

.

Without major changes to the Pictory configuration (/dev/ttyRS485 and /dev/ttyRS485-0) the error still remains.

Then, in the pictory configuration i tried to remove the ModBus RTU Master and replace it with the ModBus RTU Client, save it as start config and rebooted twice (once with RS485-0 and once without).

My main question now is, whether i need to completely reconfigure the pictory configuration from zero or if there is some tool i could use to convert it?

Best regards

[RevPiModIO]

Yes, that's right. We are currently working on another patch for this. The published updates restore the general function of Modbus in PiCtory.

[user]

Hi,

i tried to recreate the Pictory Configuration from zero up, but this will consume several dozen hours of work for renaming variable names and other things.

Can you offer some other solution?

Best regards

[RevPiModIO]

In general, it only affects fresh configurations made with PiCtory 2.17.0 and 2.17.1 on Bullseye, Bookworm and Trixie. The previous versions of PiCtory were not affected and can be operated unchanged with the new revpi-modbus version on Trixie.

Bullseye and Bookworm do not need a new revpi-modbus version.

PiCtory versions 2.17.0 and 2.17.1 have failed to write a string to the configuration file „config.rsc“. If the values remains empty, revpi-modbus cannot utilize the value for „Modbus_Client_Status“ and „Client_Status_Reset“. To use the values, you must enter the names of the IOs in the respective fields. All other Modbus values remain unaffected including the key names (with the new revpi-modbus 2.0.1 version on Trixie).

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      "extend": {
        "deviceMisc": {
          "tbl_A_rowcount": "1",
          "ModbusMasterStatus_ModbusRTUClient_20260619_1_0": "",
          "MasterStatusReset_ModbusRTUClient_20260619_1_0": ""
        },

[user]

You give me full example configuration?

I am not able to figure out where to insert it, as the configuration is a oneliner if opened with nano on my machine.

Additionally, i need more details. I think i am not able to solve problem without detailed instructions.

[user]

Update:

i was able to find the entries in the config, however my config seems to be fine.

The entries do correspond to the IO names in the pictory config.

The error is still 255.

[RevPiModIO]

Oh, I'm sorry for the config text.

It would be enough to open "Extended Data" on the virtual Modbus device and confirm with "OK". Then save the configuration again and "Reset Driver". This will also repair the configuration.