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CP 341 Modbus RTU Master - reading 32 bit registers

9/10/2014 5:45 PM	Rate (0)
dzwilu Bronze Member Joined: 12/3/2008 Last visit: 3/22/2022 Posts: 146 Rating: (4)	Dear All, I have a following problem: I want to communicate my CP341 with a LUMEL energy meter via Modbus RTU. I am able to reach the device on the network and read 16 bit registers. But the values that are important for me are stored in 32 bit registers: reg no 7500 : Voltage (as 32 bit float) reg no 7501: Current (as 32 bit float) etc The problem is that in the modbus telegramm I set the start address 7500 and length 2. In the received telegramm the number of bytes is 8... So my CP341, thinks it is a bad response. For communication I am using P_SND_RK, and P_RCV_RK blocks. Is there any way to solve this problem? Maybe somehow deactivate the check of the length in the response telegram? Thanks in advance. Regards, dzwilu

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9/10/2014 6:09 PM	Rate (0)
smiffy Platinum Expert Joined: 1/17/2007 Last visit: 3/10/2025 Posts: 1557 Rating: (540)	If you are asking for 16-bit registers (the Modbus standard) and they are actually sending you a 32-bit registers (which CP341 Modbus driver will quite rightly see as two 16-bit registers) then the Lumal vendor is invalidating the Modbus specification. As such, I think it is very unlikely that you can make the CP 341 standard modbus driver software work with it. So they should not be marketing their device as Modbus comaptible. You need to talk to them and tell them this.
	Programming today is the race between software engineers building bigger and better idiot proof programs, and the universe producing bigger and better idiots. So far, the universe is winning...
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9/10/2014 6:38 PM	Rate (0)
Kaulquappe Posts: 3093 Rating: (324)	It is for sureimpossible to make the CP341 Modbus driver work with this. Regards, Kaulquappe
Kaulquappe Posts: 3093 Rating: (324)
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This contribution was helpful to 1 thankful Users smiffy

9/11/2014 7:14 AM	Rate (0)
TIBI68 Gold Member Joined: 12/1/2009 Last visit: 2/9/2025 Posts: 672 Rating: (147)	Dear dzwilu, sometimes a second look into the manual or documentation helps. I don't know about the model of meter you have but I read from the manual of the N14thatthe data is availabale in 16bit registers (from 7000...) as well as in 32bit registers from (7500...). So using 7000 instead of 7500 should fix your problem. Best Regards.
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