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Rocky Mei

Why can't modify PLC program?

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Hi everyone! We have a problem about modify program, when we try to modify Timer, the message appears as follow: Message(386) Command not valid unless logged in Anyone who know what is means? Thank you very much! PS: We can read program, but can not write. (The PLC software is proWorx NxT, and the modul type is 984-785E.) Edited by Rocky Mei

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You must first be connected to the PLC with the proper cable, then you must "attach" (NXT lingo to begin online communications). Also the PLC must have the memory protect key in the off position and the NXT program must be in Program vs Monitor mode.

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Thanks! The cable is no problem, because I use the cable can connect another machine with 984-E255 CPU, and the memory protect key is in the off position. also I am sure NxT is in the program mode, but I don't understand "attach" means, could you explain it for me? Thank for advance!

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When you select "online", NXT should request an address for the PLC. Modicon typically defaults to one (1), but it could be anything between 1 & 255. This is the attaching process for NXT. In the much older programs, you had to perform a specific attach routine. The name attach just has stuck around. After NXT allows you to look at the logic when online, you are attached. Again, the cable plays an important part here, especially if you are using a 9 pin to 25 pin adapter on the cable. Not all of these adapters will function correctly. A common problem with them is the not logged in error.

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Hi I already solve the peoblem that we can only read but can not write program, because we config two ports for HMI and PC, if we just unplug HMI port and the PC port is still occupy, so just unplug two ports connection then we can read and write program. Maybe this is the reason.

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