Host Engineering Forum
General Category => Do-more CPUs and Do-more Designer Software => Topic started by: Schmu @ Maxam on February 01, 2013, 12:20:48 PM
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I am reading up on Do More coming from DS5. I routinely exchange contact data between my many plc's for alarm and status indications. I see no way to transmit anything other than V, etc. memory in WX/RX so far. Am I missing something with formatting or did they drop the ability to read and write the C's? Thanks for any input!
Edit, I was using ECWX and ECRX before.
Edit 2, I see through DLWX the receiving PLC can map to C contacts, but I cannot pick C or VC in the originating PLC to send it.
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With a DL Master to a Do-more Slave, the Do-more does not allow direct access to the Do-more I/O, but internal "DL Guest Protocol" memory datablocks. In the Do-more CPU, this is specifically DLX, DLY, DLC, and DLV. The first 3 are bit data-blocks, and the last one is 16 bit unsigned memory. Note that these DL guest memory areas are numbered in OCTAL, to simulate the DirectLOGIC protocol addressing that you are used to (so the bit after DLC7 is DLC10).
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I am setting up a new plant with 2 Do-More's. One does all theinterfacing in the electrical room (VFD's and sensors there) and the other runs the program and has all the process data input into it some distance away. I need to swap C's between the two. Since my post, I have seen Peerlink and have figured out, I think, how to map C data to PL data block to transmit via peerlink. Is this the way to accomplish this or is there an easier way? So many things have gotten easier, I am surprised this is made mroe difficult than a simple ECWX. Thanks for you input!
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Sorry, I thought you were needing to interface to existing DL PLCs.
PEERLINK is brain dead simple, if update rate of 10Hz is good enough, supporting up to 16 blocks of 16 WORDs "globally shared" data.
If you need faster data rates or more data, we recommend using Modbus/TCP out the DM1E's Ethernet port using MRX/MWX, which shows up in the slave's Modbus Guest Protocol memory areas (MI MC, MIR, and MHR; Modbus Inputs, Coils, Input Registers, and Holding Registers, respectively), although you can easily do DLRX/DLWX out the Ethernet port also, which will show up in DLX, DLY, DLC, and DLV data blocks in the Do-more slave.
You can also do Serial comm, which is pretty easy for point to point (built-in and H2-SERIO module), a little harder for multi-drop (see H2-SERIO4 for an RS485 port). Modbus/RTU and DirectLogic's RX/WX protocols are supported, using the same MRX/MWX and DLRX/DLWX instructions as you would for Ethernet).
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I am going to try the Peerlinks first. If not good enough, I will move on. DLC looked interesting, but the included instructions warned to stay away from the internal xC's like that. IF you think those will be ok to use, I will try those as well. Thank you very much!
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So many things have gotten easier, I am surprised this is made mroe difficult than a simple ECWX. Thanks for you input!
We agree, but there is more to the story. The traditional protocols that are used on most existing PLCs do not have the strongest security mechanisms. When we designed Do-more, we wanted to do better, and our native programming protocol does a decent job of staying secure. The comms underlying Modbus and RX/WX are not as robust though, and we chose limit the areas those protocols could access to the areas that Franji1 described. Having add copy instructions to move data in and out of the areas that can be accessed remotely is definitely harder, and we are sorry for that, but we felt that it was the right thing to do in the interest of improving security. Hopefully we gave you enough improvement that inconvenience of this is manageable. ;)
Although we really gotta find a better way to disseminate this info...this comes up petty often... ::)