Hi Folks.
I am gearing up to add a 2nd identical HMI to a project. This 2nd HMI will basically be an exact clone of the 1st one. The equipment we are controlling will be operated from either one HMI or the other, depending on the needs of the customer on that particular day. It will not be possible or allowed for 2 different people trying to operate the unit from both HMI's simultaneously. The HMI is told what screen to display by monitoring an integer value in the PLC. Both HMIs will display the same screen at any given moment in time.
My concern is, there are some pushbuttons (momentary and toggles) on some screens that trigger various actions in the PLC. So if one button is pushed while the same button on the other HMI is obviously NOT pushed, what will happen? Is the other HMI forcing that bit OFF hence creating some kind of conflict for that bit in the PLC?
I'm using a couple of Automation Direct EA9's and a MicroLogix 1400...one HMI is connected to the PLC via ethernet cable and the other is connected thru a RS-232 cable
If the bit in the PLC (which is controlled by the pushbutton) changes state as it should, even for one scan, I should be OK as in most cases I am latching something but I was wondering if anyone has any advice or input on this. TY
I am gearing up to add a 2nd identical HMI to a project. This 2nd HMI will basically be an exact clone of the 1st one. The equipment we are controlling will be operated from either one HMI or the other, depending on the needs of the customer on that particular day. It will not be possible or allowed for 2 different people trying to operate the unit from both HMI's simultaneously. The HMI is told what screen to display by monitoring an integer value in the PLC. Both HMIs will display the same screen at any given moment in time.
My concern is, there are some pushbuttons (momentary and toggles) on some screens that trigger various actions in the PLC. So if one button is pushed while the same button on the other HMI is obviously NOT pushed, what will happen? Is the other HMI forcing that bit OFF hence creating some kind of conflict for that bit in the PLC?
I'm using a couple of Automation Direct EA9's and a MicroLogix 1400...one HMI is connected to the PLC via ethernet cable and the other is connected thru a RS-232 cable
If the bit in the PLC (which is controlled by the pushbutton) changes state as it should, even for one scan, I should be OK as in most cases I am latching something but I was wondering if anyone has any advice or input on this. TY