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!

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Identifying ModBus Plus Connectors

vlcsnap-2017-07-03-12h14m03s250Please click here to link to the complete video!

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Happy Birthday, America!!!!!

Delta Building Fireworks 7-2017

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A VFD for SINGLE PHASE MOTORS!

Delta Automation, Inc. has recently partnered with Invertek to supply, install and service their line of VFDs specifically designed for SINGLE PHASE MOTORS.   This is a very niche, specific market that we here at Delta have been searching to fulfill for sometime. Many of our clients have requested this type of product, and up until now our only solution was to convert the motor to a 3 phase unit and VFD. Depending upon the frame size, this was not always the best possible solution and sometimes, just not possible at all. Now these clients utilizing these smaller motors will be able to reap the benefits of energy savings, energy rebates, mechanical wear and tear, and motor/equipment protection just as the large motor users have enjoyed. Please contact Delta to provide you with more information or a quote!00001

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Updated our Training and Conference Room

We recently updated our training and conference room, and added this Delta logo onto our white board cover.delta-decal-conf-room

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The Newest Addition to Delta’s Service Fleet!

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Unusual Application for an IDEC FT1A Touchscreen

A local Virginia facility engineer had an unusual, and mundane task to accomplish. In a newly completed housing building, the living quarters all are equipped with motion or occupancy sensor to increase the overall energy efficiency of the new building. With no motion in a particular room, the lights and HVAC systems are reduced or shut off.  These particular occupancy sensors, illuminate utilizing a green LED when sensing motion. This however, in a darkened room is very bright and disturbed  the occupants.  The engineer found no published method to extinguish the LEDs, so he contacted the manufacturer. The manufacturer explained a procedure to accomplish this task. It was however a cumbersome task, especially when there were over 1100 of these sensors involved. The procedure goes something like this: Press the programming button 20 times, wait 1 second, press the button again 2 times, wait 1 second, press and hold the button 1 second, press the button 20 times. Can you imagine performing this procedure over 1100 times without a mistake?

Fortunately, he was already a user of the IDEC FT1A touch screen for other applications there. He designed and built the “jig” shown in this quick video, to program the occupancy sensors 5 at time, error free every time!

Sensor Video

An efficient and fun project!

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Delta Employee Installed as a New NAWIC, Chapter 141, Member

lauren-nawic

Lauren Vugveteen, Deltas new accounting manager, is shown here after joining and being installed as the newest member in the Richmond Chapter 141 of NAWIC.

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Delta Automation Salutes All Veterans

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Delta Automation Strongly Encourages Everyone to VOTE Today!!!!!!

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