PLC5 - real time clock

[kake 0]

I have a PLC5/40L and a DDE link in an excel spreadsheet. The spreadsheet has a macro that records some counter values (DDE link) at the top of the hour (every hour) then the PLC sets counters to zero at the top of the hour (every hour) a couple seconds later. The clock from the PLC and the clock from the windows PC do not stay in sync. This causes zeros to be recorded on occation. How can I sync the two clocks? I cannot find an RTC function in the Thanks Kurt

[TechJunki 0]

You can do a write to S:21, S:22, and S:23 in the PLC (These are the Time Registers in the PLC-5) from VBA in excel to keep the clocks sync'd. Going from memory it would be something like: DDEPoke RSIchan, "S:21", 10 Check out the VBA DDE examples in RSLinx HELP for more info Edited 23 Aug 2005 by TechJunki

[b_carlton 61]

Another approach would be to let the PLC control the action. When the PLC clock senses the top of the hour trigger a copy of the relevant data to another set of registers, set a flag and clear the original registers. Meanwhile the VBA in excel, as it approaches the top of the hour begins watching that flag. When it goes true, copy out the relevant copied registers and reset the flag.

[Guest Guest_kake]

Thanks for your input. I will investigate these. Kurt