Just click on "OK" to accept the default TLP LogixPro selection. A dialog box will appear asking for you to select a Processor Type. If your program is not empty, then click on the File menu entry at the top of the screen and select "New" from the drop-down list. If this is the only rung visible then your program is currently empty. This is the End of Program rung and is always the last rung in any program. The program editing window should contain a single rung. From the Simulations Menu at the top of the screen, Select the I/O Simulation and ensure that the User Instruction Bar shown above is visible. We will go into more detail about this in our "What makes a TON timer tick" article but we hope this is enough to convince you that there are no additional mysterious steps for a PLC to properly track the accumulated value of a timer.LogixPro Relay Logic Introductory Lab RSLogix Relay Logic Instructions This exercise is designed to familiarize you with the operation of LogixPro and to step you through the process of creating, editing and testing simple PLC programs utilizing the Relay Logic Instructions supported by RSLogix. Observe that our mystery bits in N7:5 are now in sync with our T4:0 accumulated value. Now with I:0/0 ON, switch the PLC to "Program" mode and then back to "Run" mode. Each time you enable it, our mystery value is different.ĥ.
Note that our mystery N7:5 word changes along with the accumulated value although their values are probably not the same. Also we have placed S2:4, the free running clock's value the instant the timer was enabled in N7:4.Ĥ. To study these mystery bits further, we have copied T4:0 to N7:0 and additionally have masked the known bits, 13, 14, and 15 and placed the remainder in N7:5. That only accounts for 3 or the 16 bits of that word.ģ.
But the other word only identifies the EN (Enable), TT (Timer Timing), and DN (Done) bits. You see the the ACC (Accumulated) and PRE (Preset) take up a word each (16 bits each). That means each timer consumes 3 words.Ģ. You can see we have 40 elements that take up 120 words. On the left hand pane, right click the "Data Files" folder and select properties. One reason we chose the Micrologix 1000 for this project is it allows the copying of the T4 data table to the N7 data table.ġ. 01, it never made sense to me how the TON instruction could keep track of 32767 seconds when it has a time base of 1 second. While it is feasible for the processor to be able to update the TON's accumulated value when the timebase is. As you read more of our lessons you will find that we don't believe there are any mysteries to how a PLC functions. Most explanations of timers end with the explanations contained in the rungs above, leaving the timers internal operation somewhat of a mystery.
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