ML1500 MSG control code

Hi Everyone.

I am working on a quasi DSC project. I am using DeviceNet. I have 1 Master(HOST) connected to a Panelview+ 1500 and about 12 slave nodes connected to Panelview 300's.

Through the Hosts HMI, attributes in a slave can be change. This is accomplished simply by selecting a node and turning a feature on/off or changing some numerical value. In my code I using the node selection and the enter bit to determine/trigger a message being sent to the selected node.

I used the example given in the ML1500 instruction set reference manual for "Enableing the MSG Instruction Via User supplied Input",

MSG to node 1 has been requested, latches COMM BIT

 

     Node1                                 COMM1_L_U_OFFSET1

     B3:4/0      MG112:0/EN                         B3:21/0

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

 

Intiates message being sent

 

COMM1_L_U_OFFSET1

   B3:21/0

------][--------------------------------MSG MG112:0----

 

when message is done unlatches Comm bit 

 

   MG112:0/DN                              COMM1_L_U_OFFSET1

--------][------------------------------------------(U)----

    |       |

    |       |

    |--][---| 

 

   MG112:0/ER

 

Clears message request bit

 

                                                  Node1

   MG112:0/DN                                    B3:4/0                                                                  

-------][-------[ons]------------------------------(U)-----

                                             

Alright, everything works great...messages get sent, no errors, happy go lucky.

My problem is that when I am viewing this online the DN and EN bits remain high after the intial msg transfer. I looked at that timing diagram in the book and the EN bit should go low after the DN bit goes high...this dosen't happen.....Any suggestions or comments? Has anyone else used this example code before?

Thomas