# Access to MODBUS TCP addresses (from Raspberry Pi)

**URL:** <https://discourse.nodered.org/t/access-to-modbus-tcp-addresses-from-raspberry-pi/15820>\
**Category:** General\
**Created:** [23 September 2019 18:27 UTC](https://discourse.nodered.org/t/access-to-modbus-tcp-addresses-from-raspberry-pi/15820 "2019-09-23T18:27:44Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![sistemas](https://avatars.discourse-cdn.com/v4/letter/s/858c86/32.png) [@sistemas](https://discourse.nodered.org/u/sistemas)\
**Post date:** [23 September 2019 18:27 UTC](https://discourse.nodered.org/t/access-to-modbus-tcp-addresses-from-raspberry-pi/15820/1 "2019-09-23T18:27:45Z")

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Hi friends:

I have installed Node-RED with Modbus-Package in order to connect via TCP a Kinco PLC, which is connected to a Raspberry PI.

I set up the Node Server and it connects to the master properly, but the Node Read doesn't get any data at all. Unfortunatelly, I am not skilled at Modbus protocol, and I have no response from the PLC developer, but previously he has sent a documentation to access to every specific PCL variable.

The document describes the following addesses location:

Variable Gateway Bit  
A 401000 0  
B 401000 1  
C 401000 2  
.  
.  
X 401002 0  
Y 401002 1  
Z 401002 2

The question is: what values should I assign into the Node textboxes in order to get data from any of these variables?  
-Unit ID  
-FC  
-Address  
-Quantity

I attach my flow diagram:

 ![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/2X/d/d3756a32d7949a7359a1f81fba6bd497adb881dd.png)

Thanks so much in advance

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**Author:** ![ukmoose](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ukmoose/32/13_2.png) [@ukmoose](https://discourse.nodered.org/u/ukmoose)\
**Post date:** [23 September 2019 19:53 UTC](https://discourse.nodered.org/t/access-to-modbus-tcp-addresses-from-raspberry-pi/15820/2 "2019-09-23T19:53:52Z")

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Welcome to the forum.  
There are 8 different “modbus packages”  
[https://flows.nodered.org/?term=modbus%20&type=node&num\_pages=1](https://flows.nodered.org/?term=modbus%20&type=node&num_pages=1)  
It’s useful if you specify the name of the modbus nodes you have installed.

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**Author:** ![sistemas](https://avatars.discourse-cdn.com/v4/letter/s/858c86/32.png) [@sistemas](https://discourse.nodered.org/u/sistemas)\
**Post date:** [24 September 2019 14:21 UTC](https://discourse.nodered.org/t/access-to-modbus-tcp-addresses-from-raspberry-pi/15820/3 "2019-09-24T14:21:31Z")

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THanks ukmoose, I have installed other types, but the result is the same: 0 values.  
regards.

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**Author:** ![ukmoose](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/ukmoose/32/13_2.png) [@ukmoose](https://discourse.nodered.org/u/ukmoose)\
**Post date:** [24 September 2019 15:51 UTC](https://discourse.nodered.org/t/access-to-modbus-tcp-addresses-from-raspberry-pi/15820/4 "2019-09-24T15:51:12Z")

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That’s great, but which one are you using?

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**Author:** ![sistemas](https://avatars.discourse-cdn.com/v4/letter/s/858c86/32.png) [@sistemas](https://discourse.nodered.org/u/sistemas)\
**Post date:** [24 September 2019 16:03 UTC](https://discourse.nodered.org/t/access-to-modbus-tcp-addresses-from-raspberry-pi/15820/5 "2019-09-24T16:03:12Z")

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I have installed "node-red-contrib-modbus" and later "node-red-contrib-modbustcp" because I have to use the TCP protocol to connect the Kinco PLC.  
😉