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Node-RED Modbus read from PAC2200

8/7/2019 2:21 AM	Rate (0)
DuncanCT Advanced Member Joined: 11/16/2014 Last visit: 1/24/2025 Posts: 21 Rating: (0)	Please can someone guide me in the right directions. from the PAC2200 manual... "A.1.3 Modbus measured variables with the function codes 0x03 and 0x04 Addressing the measured variables You can use the Modbus function codes 0x03 and 0x04 on all the measured variables listed below. Note Error in the case of inconsistent access to measured values Please ensure the start offset of the register is correct when making read accesses. Please ensure the start offset and the number of registers are correct when making write accesses. Example: If a value consists of two registers, a read command applied in the second register will generate an error code. The PAC2200 will also output an error code if a write operation ends in the middle of a multi-register value." This is the Voltage VL1-N address... Offset = 1 / No. of Reg. = 2 / Name = Voltage VL1-N / Format = Float / Unit = V / Value range = n/a / Access = R What do I need to populate in the Modbus Read node? FC = ?? Address = ?? Quantity = ?? I have tried what I though was right but an not getting the correct values back in debug. Thanks in advance.
	Last edited by: DuncanCT at: 08/07/2019 02:21:30
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8/8/2019 5:37 PM	Rate (0)
Fe_lipe Silver Member Joined: 12/12/2016 Last visit: 12/11/2025 Posts: 640 Rating: (60)	Hello, You should find a description on how to use the Modbus Nodes on here. Kind regards!

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This contribution was helpful to 1 thankful Users DuncanCT

8/12/2019 6:38 PM	Rate (0)
DuncanCT Advanced Member Joined: 11/16/2014 Last visit: 1/24/2025 Posts: 21 Rating: (0)	Thanks Fe_lipe. Would the PAC2200 be interchangeable with the S7-1500 in the example flow provided? Is there any more documentation for Modbus and Node-RED?

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8/14/2019 5:35 PM	Rate (0)
Fe_lipe Silver Member Joined: 12/12/2016 Last visit: 12/11/2025 Posts: 640 Rating: (60)	Hello, It's not interchangeable but the concept should be similar: Sentron Pac provides a Modbus-Server, IOT acts as Modbus Client. Does the PAC2200 use Modbus-RTU or Modbus-TCP? The nodes should be capable of both. Here on the forum there is a tutorial video on how to use the Modbus-RTU nodes, and an example flow for Modbus-TCP for the PAC4200, which you can find in the attachment. Kind regards! Attachment PAC4200.txt (409 Downloads)
	Last edited by: Fe_lipe at: 08/14/2019 17:36:17
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