# Node-Red to HMI connection

**URL:** <https://discourse.nodered.org/t/node-red-to-hmi-connection/6626>\
**Category:** General\
**Created:** [9 January 2019 21:13 UTC](https://discourse.nodered.org/t/node-red-to-hmi-connection/6626 "2019-01-09T21:13:59Z")\
**Posts on this page:** 7\
**Page:** 1

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**Author:** ![jfehl](https://avatars.discourse-cdn.com/v4/letter/j/d2c977/32.png) [@jfehl](https://discourse.nodered.org/u/jfehl)\
**Post date:** [9 January 2019 21:13 UTC](https://discourse.nodered.org/t/node-red-to-hmi-connection/6626/1 "2019-01-09T21:13:59Z")

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I am trying to determining if there is a way to write data directly to a manufactured HMI that is capable of Modbus TCP/IP communications. I want to display values that are stored in an SQL database for example, on the HMI screen. There would be no PLC in this system. Is this possible?

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [9 January 2019 21:25 UTC](https://discourse.nodered.org/t/node-red-to-hmi-connection/6626/2 "2019-01-09T21:25:51Z")

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If it works as a modbus slave that you can send modbus data to that gets displayed then it should be possible using one of the modbus nodes. I am not certain from your description whether it does function like that though.

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**Author:** ![jfehl](https://avatars.discourse-cdn.com/v4/letter/j/d2c977/32.png) [@jfehl](https://discourse.nodered.org/u/jfehl)\
**Post date:** [9 January 2019 21:35 UTC](https://discourse.nodered.org/t/node-red-to-hmi-connection/6626/3 "2019-01-09T21:35:18Z")

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Sorry, is believe it is a slave in that regard? I am able to get modbus register data displayed to this HMI from other devices on the same network...for example I have a small Advantech unit counting pulses, and I can display the total number of pulses collected to this HMI screen. (Register 40002 for example) That device is set up with an static IP address and using port 502.

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [9 January 2019 21:43 UTC](https://discourse.nodered.org/t/node-red-to-hmi-connection/6626/4 "2019-01-09T21:43:15Z")

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I think that means that the HMI is a modbus master, and asks the other devices for data which gets displayed. Is that right? If so then you would need a modbus slave node in node red. I am not aware of a modbus slave node.

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**Author:** ![jfehl](https://avatars.discourse-cdn.com/v4/letter/j/d2c977/32.png) [@jfehl](https://discourse.nodered.org/u/jfehl)\
**Post date:** [10 January 2019 13:15 UTC](https://discourse.nodered.org/t/node-red-to-hmi-connection/6626/5 "2019-01-10T13:15:53Z")

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I believe you are completely correct, and since there is not a slave node, I may be out of luck.

Thank you

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**Author:** ![thatcadguy](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/thatcadguy/32/5273_2.png) [@thatcadguy](https://discourse.nodered.org/u/thatcadguy)\
**Post date:** [19 January 2019 05:17 UTC](https://discourse.nodered.org/t/node-red-to-hmi-connection/6626/6 "2019-01-19T05:17:57Z")

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Hi @jfehl, you are not out of luck. There is a Modbus TCP server (slave) node in node-red-contrib-modbus.

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**Author:** ![jfehl](https://avatars.discourse-cdn.com/v4/letter/j/d2c977/32.png) [@jfehl](https://discourse.nodered.org/u/jfehl)\
**Post date:** [22 January 2019 20:52 UTC](https://discourse.nodered.org/t/node-red-to-hmi-connection/6626/7 "2019-01-22T20:52:55Z")

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Ah ha, Thank you. I will go looking.....