Richviper44

In the early days of programming yes its true memory was scarce and so were timers in memory.  Now that is not really the case. I was taught to write PLC code by many high level programmers and they always wrote code as if it were in very specific steps and one step was not allowed to affect a previous step as this could cause dangerous actions.  A good example was on a press that I had to service once.....   A 4000lb ram would move via a hydraulic valve and was programmed to stop when it hit a prox.  If the prox flickered or the ram drifted out of position the ram would continue moving.  I was taught every machine and its motions were a sequence.  So in a step of this sequence is the prox is on.... Next step de-activate the valve.  Since the first step was completed it cannot happen again compared to the same prox driving the valve in the same rung would or could re-initiate the valve output.......  

Just another tip...... I have always learned NOT to have a physical input drive a output but drive a internal bit and Proxies / switches should always be debounced with a timer as these can cause grief and strange acting logic which is also very difficult to troubleshoot.  

I am trying to get the data from a 1746-NI8 module using the message command (MSG) in RSLogix 5000. Setup is 1756-L63 processor with a SLC remote rack (12 Slot) that has a 1747-ASB in slot 0 and dip switch settings seem correct with specialty module selected. The NI8 is in physical slot 9. Rack is setup as Rack 0, 3/4 Rack and 6 I/O groups two slot addressing (so alternate input module then output module using). I am therefore assuming the data for the NI8 starts at group [4] as [0] to [3] is used up by the other modules. Message Config is setup as Block transfer write for one MSG and read for the other.  Number of Elements currently set for [8] as there are 8 channels. In the message command under communication/Module address should I be putting the NI8 module information here or the information for the ASB here? I have green flashing lights for the two analog input channels that are configured.  But doing some reading this usually means the NI8 hasn't received the config data so that is why I ask this question. Read and write messages seem to work but I am also unsure of the number of elements that need to be read and written as most of the documentation for the MSG command is PLC to PLC in the knowledgebase at AB. Any help is greatly appreciated.