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| 3/5/2010 1:20 AM | |
Joined: 10/7/2005 Last visit: 9/28/2023 Posts: 2988 Rating:
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Unfortunately NOT dear plaid,DPV1 capability only exists if the interface is set toDP Master and you can verify this for yourself in THIS technical specification pdf. Even though DPV1 related acyclic data record read/writes can be a very useful thing for all sorts of DP Slaves (e.g. Simocodes, Softstarters, Drives etc.) to get a wealth of non time critical additional info/values from the device, they do require that data records/data sets are implemented into the device by the manufacturer. With aaCPU as a DP Slave (aka"I-Slave")it would probably become a cumbersome affair for the manufacturerto define the data records, let alone making them configurable (which is what you would require to put your userdata into them). On top of that thereis always someextra coding effort to read theDPV1 related acyclic data records. Anyway, there's a couple of possible solutions in your case; 1.) Set your S7 CPU up as a DP Master, buy two DP/DP couplers and you can then exchange a total of 488 bytes each way (244 bytes per DP/DP coupler which is the limitof any DP Slave). (and if you everneed more than 488 Bytes, simply add another DP/DP coupler to it) 2.) Set your S7 CPU up as a DPSlavewhich now limits you to exchange up to 244 Bytes of data each way. To get more data across, multiplex the data "piepline"(e.g. create your own "data header" to let the partner know where the attached "real' user data is meant to go). I'd personally opt for solution 1 even though you'll need to spent money on the DP/DP couplers (option 2 requries a bit of coding effort andyou'll need to be especially mindful about data consistency in this case too). I hope this helps |
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| 3/8/2010 7:38 PM | |
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Posts: 4 Rating:
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Thanks fritz. Thats unfortunate, but I see your point on implementing DPV1 on a CPU. I was hopingthat DPV1 acylic reads would let me useProfibusmuch like Modbus. But I don't think Profibus is meant for this -although youhave a slick way around the 244 byte maximum in solution #2. Instead using a Profibus Master module in the AB ControlLogix rack,we are now considering theProsoft ILX56-MM module. Apparently this will letaControlLogix PLCread / writedata directlyfrom an S7 PLC (via industrial ethernet) with no programming in the S7 PLC. I'll let you know if this option works out. It seems to good to be true. http://www.prosoft-technology.com/content/view/full/13843 Shawn. |
| 3/9/2010 8:09 AM | |
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Joined: 10/7/2005 Last visit: 9/28/2023 Posts: 2988 Rating:
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Hello plaid many thanks for the update, the Prosoft ILX56-MM module does indeed sounds like an interesting product(and one I haven't heard of yet). Please keep us posted about the outcome, since ProSoft have however been workinginthis area for manymany years, this one will hopefully bea case of "Not to good to be true". Since you now evalute other means of communication betweenA/B and S7, you may also be interested in the link below for complteness (which has the Prosoft ILX56-MM moduleway missing from it, I guess Siemens does not yet know about this onetoo): Connection of SIMATIC components with Allen-Bradley/Rockwell components |
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Cheers |
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