Read and participate in active technical discussions with automation and industrial controls users from all over the world.
Control.com - Nerds in Control
Member Login
Modbus Links
Search
Jump to a Date
Cool stuff
RSS Feed
Use this link to get an RSS feed of the Modbus Community article flow, for private, non-commercial use only:modbus.control.com/rss/
To get a personalized feed, become a member at no cost.
What is a good DNP3 testing software?
Want to understand Modbus Function code 126 (Hex 7E)
Siemens WinCC HMI package to communicate to a Modicon Momentum PLC using MODBUS interface
New Replies:
WinCC version 5.1 does support modbus master driver. I am not sure about the later versions of it....
Getting Kingfisher to communicate with wonderware via modbus
Modbus communication problems with Telemeq. Altivar 31. AB micrologix 1400ML.
New Replies:
By Jerry Miille on 14 August, 2009 - 8:04 pm -
You do not specifically mention it but is this an RS485 connection? I suspect that it must be...
Return strings from Modbus simulator application differ from that of HVAC system harware
New Replies:
By M Griffin on 14 August, 2009 - 1:38 am -
You haven't really given us enough information to go on. The most common problem that people have...
By Mark on 13 August, 2009 - 8:55 pm -
Hi,
I do not see enough information to determine exactly what is wrong. One thing I do see is...
It is not unusual to have byte reversal issues. One of the devices, Host or Slave, should have a...
By Carl on 13 August, 2009 - 8:41 pm -
The register number could be off by a one, depending on whether the registers are numbered from...
By Jerry Miille on 13 August, 2009 - 8:04 pm -
You are probably reading the "wrong" register. There are two addressing methods commonly...
Convert SIMATIC to MODBUS address
New Replies:
To poll Address 11, Reg 40001 for 2 Regs:
0B 03 00 00 00 02 C4 A1
To poll Address 12 register...
Need a 'software serial port' that will allow my modbus RTU software to communicate with a modbus TCP/IP device
New Replies:
I think you should use APC-Aftek's Protocol Converter (APC) series provide a solution for reliable...
I don't know about a software solution, but I have experience using the Digi One IAP, which...
Can I use the Modbus frame size larger than 256 bytes?
New Replies:
The answer is NO
The volume and speed of data you wish to exchange between both the client and...
By M Griffin on 7 August, 2009 - 11:00 am -
It's hard to suggest a good alternate protocol without knowing a lot about the application. So far,...
Thanks very much for all your reply.
In my case, I am in control of both ends.
I need to...
By Mark on 7 August, 2009 - 8:07 am -
Hi,
Since you are controlling both ends it might be advantageous to create your own.
FTP...
Thanks very much for your reply.
In my case, I am in control of both ends.
I need to transfer...
By Jerry Miille on 6 August, 2009 - 12:33 pm -
If you are going to use Modbus, you are limited to a maximum of 255 bytes of data per message...
By M Griffin on 6 August, 2009 - 12:13 pm -
If you change the protocol it won't be Modbus anymore and it won't talk to Modbus devices. If...
No! If you notice in the Function Code 3 slave response the 3rd byte is the byte count of the data...
By Mark on 6 August, 2009 - 8:12 am -
Hello,
The quick answer is no.
"A protocol is a set of rules which is used by computers...
Cable length limitations for the DP-PA couplers and LInk
from the Automation List department...
Modbus communication between S7 CP341 Modbus Master and other Modbus SlaveI have problem with modbus communication between Simatic PLC CP341 Master and a modbus slave.
New Replies:
By boy on 3 August, 2009 - 5:18 am -
Hi,
What address should we input at LADDR parameter?
Thanks...
Web HMI for HVAC
New Replies:
By Mark on 1 August, 2009 - 4:52 pm -
Hello,
PeakHMI might be a good fit for you.
Good luck,
Mark
http://www.peakhmi.com/...
By M Griffin on 1 August, 2009 - 11:49 am -
I have a free web based HMI called "HMI-Server" that might be suitable. You can download...
Is it possible to convert Modbus signal from a field device to HART either in the field or in safe area ?
New Replies:
Here's an old thread with some info regarding modbus->hart conversion...
...
Check out the Modbus Organization's Modbus Device Directory (http://www.modbus.org/devices.php)....
Does anyone have a favourite lightning arrestor / in-line surge suppressor that does not mess up a Modbus Plus trunk run?
New Replies:
By Ray Zimbal on 30 July, 2009 - 10:23 pm -
I agree with Daniel, take a look at Dehn & sons www.dehn-usa. They specialize in lightning and...
Trouble communicating NI visa in labview with the modbus protocol used by watlow F4S temperature controller.
How do I handle Modbus broadcast requests on TCP when I convert it from a serial bus?
New Replies:
By John Correa on 29 July, 2009 - 7:15 pm -
In Modbus RTU broadcast is achieved using 0 as the slave address. TCP only encapsulate RTU frames...
By M Griffin on 28 July, 2009 - 12:18 pm -
Modbus/TCP uses TCP/IP to deliver the messages. Therefore, broadcast is a TCP/IP feature, not a...
By Fred Loveless on 28 July, 2009 - 10:00 am -
TCP is a a connected state. In order to communicate to a Device that is using TCP you have to...
Protocol Converter from MODBUS RTU to proprietary protocol(HAI Omni-Link II protocol) on TCPIP
New Replies:
Solutions from the simpler to the harder:
1.- Consult HAI if they have modbus rtu option cards.
...
By Andrzej on 29 July, 2009 - 9:12 am -
Hello,
You should choose microcontroller with ethernet and serial port. For example Luminary...
How many slave devices cab be multidroped on RS-485 bus?
New Replies:
By Bud on 29 July, 2009 - 6:27 pm -
A couple years ago, I ran into a specific vendor's single loop controller that limited the number...
By M Griffin on 29 July, 2009 - 12:11 pm -
This is an electrical limitation of RS-485, not something to do with the protocol. It has to do...
The Master is just another device, so 32 including the Master is your correct answer. Remember, the...
By Andrzej on 29 July, 2009 - 9:07 am -
Hello,
One Master and 31 slaves = 32 devices. The master is the device as a slave.
Regards
...
By Ramu on 29 July, 2009 - 7:44 am -
Hi,
For RS485, its 1 + 31.
Ramu...
Your use of this site is subject to the terms and conditions set forth under Legal Notices and the Privacy Policy. Please read those terms and conditions carefully. Subject to the rights expressly reserved to others under Legal Notices, the content of this site and the compilation thereof is © 1999-2009 Nerds in Control, LLC. All rights reserved.