Home » Categories » Protocols » Modbus

My RX light is on solid, what might that indicate?
Article Number: 561 | Rating: Unrated | Last Updated: Fri, Jul 17, 2015 at 10:32 PM
If the RX light is on solid on your modbus serial port and:

The port is in RS485 mode- This is usually indicative of polarity being reversed (ie. positive is connected to negative instead of positive to positive). Try swapping the wiring to pins 1 and 8 on our port.

The port is in RS232 mode- This suggests that a constant electrical signal is hitting our receive pin which should never occur during normal operation. We have seen this on occasion with customer USB to serial converters which are not set up correctly, we strongly recommend trouble shooting your USB to serial converter if this is the case. If there is no converter involved, we recommend verifying the wire connected to our RX pin is connected to the correct pin on the other device.

If none of these common causes seem to be causing your RX to be on solid, please call Prosoft Technical Support to trouble shoot your issue further.
Custom Fields
    Posted by: Administrator - Fri, Jul 17, 2015 at 3:37 PM This article has been viewed 7705 times.
    Filed Under: Modbus
    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.
    Icon Add Comment
    Name
    Email (Required, but not published)
    Comment
    Security Code Security Code
     
    Related Articles RSS Feed
    Do any Prosoft modules support Modbus UDP?
    Viewed 1 times since Mon, Aug 24, 2015
    Can Modbus support redundant masters?
    Viewed 1 times since Tue, Nov 28, 2006
    How do I enter a Modbus address of 40001 or higher in the DevAddress command field of my MVI56-MCM?
    Viewed 1 times since Tue, Nov 28, 2006
    Read Commands from my Modbus Master to a ProSoft MCM Slave are working but Write Commands are failing. How do I fix this?
    Viewed 1 times since Fri, Feb 8, 2008
    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
    What's the difference between Modbus ASCII and Modbus RTU?
    Viewed 1 times since Wed, Mar 19, 2008
    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
    If I am reading the value from ProSoft 4x register, and it represents a digital input or digital output, how is the value stored?
    Viewed 1 times since Tue, Nov 28, 2006
    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 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
    • Icon SubscriberSubscribe to Article
    • Icon PrinterPrint Article
    • Icon EmailEmail Article to Friend
    • Icon PDFExport to PDF
    • Icon MS-WordExport to MS Word
    • Icon TwitterTweet This Article
    • Icon DiggDigg It
    • Icon StumbleuponStumble Upon
    • Icon de.icio.usDel.icio.us
    Article Rating (No Votes)
    Rate this article
    Powered by PHPKB Knowledge Base Software