Friday Afternoon Emergency

Delta received a call mid-afternoon last Friday with an emergency need for six obsolete, Modicon B246 output modules. Our stock was checked and there were plenty of these units in stock. However, these units have a very high failure rate component in them, so each unit would need to be properly tested before we could ship them overnight to the client. The latest that we could have them ready to ship was 6:00. It was already 3:00. As luck would have every unit had at least one of these components bad. A quick triage was performed to determine which units could be repaired the quickest. We informed the client that all of these units needed repair. The client said that they could live with just 4 units overnight and the remaining two on Monday. Our repair technicians went to work. They repaired and tested four of the units. They were packed up and shipped in time. The client received the units early the next morning and they kept his equipment in production. This is the type of service that Deltas’ clients have come to depend upon when they need it most!

B246

Delta Automation is Prepared to Assist any or all of our clients in the the wake of the Hurricanes

Graphic courtesy of NOAA

cone graphic

Delta Automation is prepared to assist any or all of our clients that were in the path of Harvey or may be in the path of  Irma. Our stock of new and refurbished equipment is ready to go to get you or your clients equipment up and running as soon as possible.

Our field service team will be on alert to assist with any on-site needs as well.         Please don’t hesitate to contact us via phone or email!

804 236 2800 or 1 888  PC DELTA          Email:  sales@deltaautomation.com

 

Consequences of Duplicate Addresses on a ModBus Plus Network

As with any addressable network, having duplicate addresses is an issue. On Modbus Plus networks, one of three things can occur. Modicon technical support disagrees on this subject but in my 30+ years of working with these networks all over the world, I have proven differently many, many times.

The first, and most likely event to occur,  the node that is being added to a network with the same address, will simply not be allowed to join the network.

The second thing that may occur, the node that is being added to the network will displace the existing node with the same address, assuming its’ place upon the network.

The third thing that may occur, is that when connecting the new node to the network with an existing node address is that the two nodes alternate joining and dropping off of the network.

The second and third options are obviously not desirable results. For this reason ALWAYS be certain of what addresses are existing on any given network. Utilizing a network discovery tool such as MBPStat, should eliminate any dual addressing.

Very recently, while performing a quick troubleshooting procedure upon a Modbus Plus network, I found a unique situation. I knew that I had a duplicate address on my computers’ PCMCIA card. however the plant was down, with no equipment running , and I was just doing a quick error check after repairing an illegal splice on the network. I was located at the MB+ repeater between segments 3 and 4 of this network. I monitored segment 3 for errors, all was OK, then I monitored segment 4 for errors, again all was OK. I reconnected the cables back to the repeater and then went to the end of segment 4 to monitor the entire network for errors. I was surprised to see all “U”‘s on every node! Those familiar with MBPStat, know that this indicates the monitor cannot properly identify the nodes. I went back to the repeater and checked both segments individually, again, all was OK. It was then that I remembered that I was utilizing an already assigned node address. I suspected this may be the issue. I again reconnected the cables back to the repeater, went to the end of segment 4,  reset the address to a non-assigned node address. Upon checking the network monitor, it now showed all nodes properly with no errors.This further illustrates the unusual results which may occur in the event of a dual node address.

This is even more reason to be aware of existing addresses when adding any nodes to a network!

Modicon Network Certifications

From the day after Christmas on through fours days past the New Years holiday, two teams of Delta Engineers were busily working long 12+ hour days testing, repairing and certifying Modicon remote I/O and Modbus Plus networks during a plant holiday shutdown. This project included over a dozen production lines, each with both, remote I/O systems and ModBus Plus systems.  Almost all of the Modbus Plus systems had multiple (up to 4) segments. This made for a total of 59 separate and individual certifications performed.

All of these systems had been experiencing issues and required repair. Many previously unknown issues and problems were found and repaired.  Additionally, dozens of undocumented changes, modifications, replaced/updated equipment, spare connections and hidden splices were located, documented, and repaired where necessary.

Upon bringing the plants production lines back up, after being down for 10 days, all of the newly certified systems came up with no issues or errors.

Shown here is the collection of certification reports, one for each line and system, that were provided to the client. The documents show and detail the repairs, all of the test results and any recommendations for the network. These reports prove to be invaluable in times of additions, modifications or troubleshooting.Certification reports

Call or email Delta Automation for more information or a quote on certifying your networks!