Dobrý den pane Novotný,
ve zkratce - ano, je to možné a nepotřebujete na to ani Mervis.

Součástí operačního systému, který dáváte na kartu, je ModbusTCP server, přes který můžete ovládat veškeré vstupy-výstupy vyjma sběrnice 1-Wire. Tento server není typicky dostupný zvenčí ale je možné jej přenastavit tak, aby byl dostupný na portu TCP/502. Můžete tak k PLC jednotce, která se chová jako Modbus Slave, přistupovat z libovolné aplikace, která Modbus podporuje (například pomocí zmíněných Java knihoven). Seznam Modbusových registrů a coilů naleznete zde.

Druhou možností je použít API našeho softwaru Evok, kterým taktéž můžete ovládat celou jednotku a to včetně zařízení na sběrnici 1-Wire.

Tutoriály na tyto způsoby komunikace budeme připravovat v následujících týdnech.

S pozdravem,
Martin Kudláček

Hi Jonathan,
do you have some touch screen from previous installation, or do you plan to purchase a new one? Generally speaking, the touch screens in industrial automation are equipped with PC (Pro-face for example) running custom HMI software, which communicates with PLC e.g. via Modbus. In this case, you can use Axon with no problem.

@boy-lenssen And I really recommend you to purchase the USB-RS485 converter. It is extremely handy for such debugging and it costs around $1 on eBay.

Dobrý den Dalibore,
toto je velmi jednoduché. V MervisIDE přidáte na PLC "Serverový kanál" a nastavíte protokol na ModbusTCP. Přidáte serverové zařízení, nastavíte mu IP adresu, port a modbusovou adresu, na které bude přístupné. V detailu zařízení pak namapujete registry a coily na příslušné proměnné. K proměnným pak přistupujete přes síť z libovolného Modbus Master zařízení / programu.

Místo ModbusTCP je možné použít i ModbusRTU, kde nakonfigurujete příslušný RS485 port a nastavíte modbusovou adresu.

Nemám ověřenou funkcionalitu na starém IDE (2.0.x), ale v novém, které bude začátkem září je toto plně funkční.

Martin

Hello @jakub, the pin header of the Raspberry Pi inside of the Neuron is not accessible and there is no space inside of the Neuron for such additional devices.

Hello @cvrcejir,
unfortunately this is an error in the REST API, not the Evok's web interface. I forwarded this issue to the programmers and let you know once it is fixed.

Thank you for your patience,
Martin

Hi @Martijn-Hemeryck,
it depends what type of output your sensor has. Basically there are PNP (sourcing) and NPN (sinking) outputs.

• PNP (sourcing) typically outputs supply voltage of the sensor when the sensor is in ON state otherwise it is unconnected (high impedance).
• NPN (sinking) shorts the output against GND when the sensor is ON, otherwise it is unconnected (high impedance).

For example digital outputs on our units are NPN.

If your sensor has PNP output and its supply voltage doesn't exceed 24V, you can typically connect it directly to the UniPi's digital input.

If your sensor has NPN output, that's where it gets a little bit tricky. Digital inputs can only distinguish the ON state (voltage 5-24V). Any other state - be that 0V, short to the ground or high impedance (nothing connected) will result in OFF state. In order to use NPN sensor, you need to define the OFF state by connecting the NPN output to supply voltage via pull-up resistor. And there are two ways how to do it, depending on the supply voltage of the sensor

The pull up resistor will bring the OUT to the level of the supply voltage. In the first example it is 24V, in the second example it is 12V. The GND of the UniPi and the GND of the second power supply may or may not be connected, depending on the level of isolation you need between UniPi and the sensor. But that's another story. But the DIGND has to be connected in both cases.

Martin

Hello @stevenhendrickx,
I'll start from the end - the RaspberryPi running an InfluxDB. I can only guess - and correct me if I am wrong - but you have only SD card with the Raspbian in your RaspberryPi, right? The SD cards are quite fragile regarding the number of data you can write on them. That's the reason why we switch the filesystem in MervisOS to read-only. So generally, running a database on the SD card is not-so-good idea.

Now to the part how to access Mervis variables from outside. Currently the most straightforward method is via Modbus. If you haven't use Modbus before, please take a look on the protocol itself: physical layers, addressing, datatypes,... The Wikipedia article is a good (a bit too complicated) start.
Then check our tutorial how to setup ModbusTCP server (slave) in Mervis: https://kb.unipi.technology/en:sw:01-mervis:setting-modbus-server-hidden
And to put it together check this Python Gist how to poll data from ModbusRTU slave into InfluxDB: https://gist.github.com/sansal54/bea2526ab8e968351a85db3410cc9f65

There's a lot of information you need to grasp from the beginning to get it working. Feel free to ask more.

Martin

Hi @martijn-hemeryck,
some of the dependencies are quite tricky and we weren't able to handle the transitions between new package names gracefully. The repo is reachable, however the URL has to end with slash: https://repo.unipi.technology/debian/

Best regards,
Martin

The problem has been solved by flashing the latest firmware.

Hi @mkb,
I have replicated the configuration (cycle 9999, prescaler 9599, that means resolution 0-10000 with frequency 0.5hz). I put the value 5000 (the 50% for the given resolution) to the PWM variable and was able to read a voltage change across DO1.1 and DOGND with a multimeter. The values changed in 1s interval, which they should with given frequency and duty cycle.

The last piece of SW is called a firmware (FW), which is flashed in the IO boards. Each of the group (you have 3 on the L513) has its own microcontroller running its own firmware. This needs to be up-to-date as well. I looked in our stock system and it shows that your PLC has been shipped with FW 5.5, which is very old.

The firmware cannot be updated via Mervis IDE, but only via SSH connection to the PLC. Please, let's continue via support@unipi.technology.

Thanks,
Martin

Hi @mkb, in your schematic, you don't have the DOGND tied to the GND of the 12V PSU. Please start with that.

Hi @mkb,
the picture is probably worth a thousand words:

Hi @Matt,
please use the appropriate version of the image. It should work with the image 1.9, but for the Mervis 2.2.x use the 2.2.x image: https://kb.unipi.technology/en:files:software:os-images:00-start#axon_mervis_os

Hello @Lebowski, in our PLCs we use the full-version.

Best regards,
Martin

Hello @Petr-Helebrant,
you can use Digital Indicator for that. In the settings, you can assign different images to different states of an integer variable.

Best regards,
Martin

Hello @Kermit,
you are looking for something which doesn't exist. The ModbusTCP service is not available for the Unipi 1.1 since the architecture is very different from the Unipi Neuron and Axon.

You can access to the IOs via methods described in the technical documentation - directly accessing the GPIOs and communicating with the I2C ICs.

Or you can use Evok API (https://github.com/UniPiTechnology/evok), which will make the IOs available via different web-based APIs.

Best regards,
Martin

Hello @smarko,
putting hard delays is a bad idea, even in Arduino. You can start a delay timer and with each cycle check if it finished. When it finishes, you can perform the desired action.

Best regards,
Martin

Hello @LubomirMaron, you can always flash the SD card with the clean image. Then do the licensing and then upload the solution.