Latching and UnLatching in Modicon 984 ProWorx

We have a simple circuit that we want to latch and unlatch. The ProWorx software offers a Latching Coil -(L)- instruction, but we have no clue as to unlatch. I searched the forum here and read the manual and the help section in the program, but to no luck. We anybody have any knowledge about this?

Hi

I'm afraid you'll have to do your latching the 'long' way on the Modicon...it doesn't support set & reset of discrete coils....

The -(L)- coil is a retentive i.e it remembers its last state after a controller
power down.

regards

Kevin H

www.krkautomation.com

......although if you r_e_a_l_l_y want to use S/R and you're using a Quantum, you can set & reset the bits in a 4xxxx register using SBIT & RBIT and test for them using NOBT & NCBT....

984 Ladder Logic is the base language of the Proworx, Modsoft, and other software packages (except Concept and Unity). 984LL does not have Set or Reset coils, you need to create your own logic. However the Quantum family of processors has an enhanced function set which includes these functions using the SBIT and RBIT commands.

ADVISORY: The 984LL -(L)- latch coil does not behave like a most retentative coils. You still need to create additional logic to get a true retentative coil. If the -(L)- coil was set at the time when the processor cycles down it will only be set for one scan at power up.

For a true retentative set-reset operation, of coil 0x1, I have used this logic.

  SET    RESET      0x1

---][--|-]/[--------(L)-

       |

  0x1  |

---][--|

thanks for the inputs, they have been helpful. with creating some new networks and adding some instructions, we've accomplished what we aimed for. prety much did what Jim Dungar was stating. thanks again for the info.