KB Home \| Advanced Search \| News \| Ask Question
ProSoft Knowledge Base

How do I enter a Modbus address of 40001 or higher in the DevAddress command field of my MVI56-MCM?

Article Number: 55 | Rating: 3/5 from 8 votes | Last Updated: Wed, Jul 2, 2014 at 6:34 PM

Since the Dev Address field is a signed 16-bit integer, the maximum positive value accepted by RSLogix is 32767

However the Dev Address field is a Modbus offset value. When using a Modbus function code 3, 6, or 16, an address base of 40001 is assumed. The Dev Address field is an offset from this base.

Examples:

If an address of 40001 needs to be accessed, then a Dev Address of 0 is used (40001 - 40001 base = offset address of 0)
If an address of 41031 needs to be accessed, then a Dev Address of 1030 is used (41031 - 40001 base = offset address of 1030)

If the required OFFSET actually exceeds 32767, add 65536 to calculate the signed value of this address, and that value will be accepted as a signed 16 bit INT.

Custom Fields

Attachments (0)

Attachments

There are no attachments for this article.

Comments

Comments

There are no comments for this article. Be the first to post a comment.

Related Articles

What Modbus address would we need to put into the MODSIM32 simulator if we specified on the MVI56-MCM device address to 8680HEX (-31104 decimal) when the MVI56-mcm is the slave?

Viewed 1 times since Tue, Nov 28, 2006

I have multiple Modbus masters that need to communicate with 1 or more Modbus serial (RTU) slave devices. What product should be used??

Viewed 1 times since Tue, Jan 23, 2007

How can a module's Modbus port, configured as a Slave port, detect communication loss with the Master port?

Viewed 1 times since Tue, Nov 28, 2006

Can Modbus support redundant masters?

Viewed 1 times since Tue, Nov 28, 2006

I have a ProSoft Modbus Master solution and would like to know, is the Slave Status List the best place to monitor for communications health of the network?

Viewed 1 times since Tue, Mar 18, 2008

My RX light is on solid, what might that indicate?

Viewed 1 times since Fri, Jul 17, 2015

How do I monitor the health of coms to my slaves when the module is a Master?

Viewed 1 times since Wed, Nov 29, 2006

How can I detect the feedback status of individual command successful or failed?

Viewed 1 times since Wed, Nov 29, 2006

I have limited or no experience with Modbus. How can I find out more about the protocol and command structure?

Viewed 1 times since Tue, Nov 28, 2006

Why is the bit or coil level data incorrect?

Viewed 1 times since Tue, Nov 28, 2006