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J
MODBUS Server device with relays?
You may be able to use the ICC Mirius gateway in conjunction with larger relays that accommodate the 400V 25kW 3Phase requirement. http://www.iccdesigns.com/protocol-gateways/66-mirius.html The Mirius can be configured as a Modbus RTU Master and has 2 dedicated I/O channels that can be...
jschulze
Post #8
Yesterday at 8:39 AM
Forum:
Modbus
J
MODBUS Server device with relays?
Can you clarify your requirements? "Poll one MODBUS register continously" seems to imply you're looking for a Modbus client/master device as opposed to a server/slave device. Is this correct? What version of Modbus do you need (serial Modbus, such as Modbus RTU or Modbus ASCII, or Ethernet...
jschulze
Post #3
Wednesday at 8:29 AM
Forum:
Modbus
J
Energy Analyzer interfacing via Modbus protocol
It's unlikely anyone here will be familiar with the data logger software you're using. Therefore, I recommend you diagnose and troubleshoot this issue using Modbus Poll only, which many users here have used and are familiar with. In addition, Modbus Poll allows you to view and log the...
jschulze
Post #6
Apr 10, 2024
Forum:
Instrumentation & Measurement
J
ABB PM573 ETH - after 1 valid poll and response the Modbus communication terminates.
ModScan will open a Modbus/TCP connection and keep it open while making requests (it does not close the connection after each request/response). Therefore, it sounds like the ABB is closing the connection prematurely. You may need to change your Modbus TCP/IP Server Settings on the ABB. Take a...
jschulze
Post #2
Apr 5, 2024
Forum:
Modbus
J
Has anyone worked with Brodersen RTUs?
As long as the RTU has more than one serial port, it seems you can run Modbus Slave and Modbus Master simultaneously. Note that at least two serial ports are required because Modbus only allows one master on each RS-485 bus. From my brief research into the Brodersen equipment, it seems they are...
jschulze
Post #2
Apr 1, 2024
Forum:
Modbus
J
How to protect Modbus TCPIP server from connecting more than Max number of connections, new connection causing dropping of old connections
Well, to be blunt, if you're implementing this yourself, the behavior is going to be exactly what you coded it to do (after all, computers only do what you tell them to do). It seems currently, you've implemented it to unconditionally reuse sockets, thus dropping a previously established socket...
jschulze
Post #2
Mar 28, 2024
Forum:
Modbus
J
Modbus RS-485 Checksum and insufficient bytes received errors
I think that might be your issue. I can't find any documentation or indication online that the LZQJ-XC or VARIOMOD-XC support the Modbus protocol. If you need Modbus with the LZQJ-XC, it seems you may need to use the LKM614 from REDZ instead of the VARIOMOD-XC. However, I would recommend...
jschulze
Post #10
Mar 27, 2024
Forum:
Modbus
J
What is difference of INPUTS and OUTPUTS in Modbus
This statement is not true. I just provided you with an example in my previous post of real-world INPUTS (a flow sensor) and OUTPUTS (relay contacts) connected to a flow meter and how those would map to Input Registers (INPUTS) and Coils (OUTPUTS) on Modbus. I did not provide you with any of...
jschulze
Post #4
Mar 27, 2024
Forum:
Modbus
J
ACE949-2 communication rs485
Take a look at these excerpts from the Modicon M340 User Guide and Sepam Series 20 User Guide.
jschulze
Post #2
Mar 26, 2024
Forum:
General Automation Chat
J
Modbus RS-485 Checksum and insufficient bytes received errors
Another follow-up question. What module are you using with the EMH meter to provide RS-485 Modbus RTU? Are you using the VARIOMOD-XC from EMH or another module, such as the LKM614 from REDZ?
jschulze
Post #8
Mar 26, 2024
Forum:
Modbus
J
Modbus RS-485 Checksum and insufficient bytes received errors
Thank you for the additional details. Can you please describe or provide a diagram of how you have your EMH meter wired to your RS-485 to USB converter? What happens if you swap your + and - wires at one end? Can you tell us what Modbus software you're using on your PC. Please also include a...
jschulze
Post #7
Mar 26, 2024
Forum:
Modbus
J
What is difference of INPUTS and OUTPUTS in Modbus
I believe you're thinking about it on too wide of a scope. Don't think about it from a communication perspective or from your whole system (i.e. one device sending values to another device, etc.). The Modbus slave alone defines whether specific data is INPUT data or OUTPUT data. INPUT data is...
jschulze
Post #2
Mar 25, 2024
Forum:
Modbus
J
MIL 1553B to RS485/RS232 connectors/converters
Performing a Google search for "MIL 1553 to RS-485 gateway" turned up this device: https://www.mil-1553.com/macc-communications-converter Perhaps that would work for your needs?
jschulze
Post #2
Mar 22, 2024
Forum:
General Communications Chat
J
Netbiter IOX-8AIV - Checksum Error in Repsonse Message - Modbus RS485 modscan
I believe these are the only connections you need to make: Dtech Adapter Netbiter T/R+ (DB9 pin 1) A T/R- (DB9 pin 2) B GND (DB9 pin 5) GND (VDC-) No wires need to be connected to RXD+ (DB9 pin 3) and RXD- (DB9 pin4) on the Dtech adapter.
jschulze
Post #20
Mar 18, 2024
Forum:
Modbus
J
Netbiter IOX-8AIV - Checksum Error in Repsonse Message - Modbus RS485 modscan
Thank you for the USB to RS-485 adapter documentation. According to that documentation, you do not need to connect jumper wires to the adapter. Refer to the image under 6. Connection instructions->Type-C TO RS485->2. RS485 point-to-more/ half duplex 2-line communication. You should have wires...
jschulze
Post #18
Mar 18, 2024
Forum:
Modbus
J
Modbus RS-485 Checksum and insufficient bytes received errors
Unfortunately we cannot be more descriptive with our responses until you are more descriptive in explaining the problem. We need to know all equipment involved (vendor and models), what Modbus software is being used (if any), what USB to RS-485 adapters are being used (if any), the exact steps...
jschulze
Post #5
Mar 15, 2024
Forum:
Modbus
J
Netbiter IOX-8AIV - Checksum Error in Repsonse Message - Modbus RS485 modscan
If swapping your A and B wires results in the same behavior as when the Netbiter is off or when the RS-485 wires are disconnected, then it is very likely the wrong polarity and you should swap the wires back. You should not be receiving a "Received invalid response to modbus query" when the...
jschulze
Post #16
Mar 15, 2024
Forum:
Modbus
J
Modbus RS-485 Checksum and insufficient bytes received errors
A Modbus RTU checksum error is not caused by parity. The Modbus checksum is at a higher level. The parity bit in each character is a sort of checksum, but on the scope of each single character in the Modbus frame. The Modbus checksum is performed after successful reception (i.e. no parity...
jschulze
Post #3
Mar 15, 2024
Forum:
Modbus
J
Netbiter IOX-8AIV - Checksum Error in Repsonse Message - Modbus RS485 modscan
What error message does ModScan show if you disconnect the RS-485 wires? If it doesn't show a timeout error, there may be an issue with your USB to RS-485 adapter. You may need to try a different adapter. When you swap the A and B wires, it should be done at one end only. The Netbiter does...
jschulze
Post #13
Mar 14, 2024
Forum:
Modbus
J
Netbiter IOX-8AIV - Checksum Error in Repsonse Message - Modbus RS485 modscan
When communications is successful, ModScan's Polls and Responses counters will increment together and there will be no messages in red text at the top. As for which registers to access on the Netbiter, refer to page 32 in the manual I linked in my previous response. Analog Input 1 is register...
jschulze
Post #10
Mar 14, 2024
Forum:
Modbus
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