There are many different options for programming in Proficy Machine Edition, each with their own unique advantages. Ladder Logic should be the go to option for writing control portion of the software. Ladder Logic tends to be easier to debug and operates more reliably than scripting.

Scripting is most useful when designing the HMI. In scripting the programmer can access CSV files, modify HMI objects, apply unit conversions, and change languages. Further, scripting comes in two varieties, ViewScipt and VBScript, and 3 different scopes. Good program management and proper planning of a project will include all of these options for a clean and well designed program.

Horner’s EGD communication protocol seems to slow down CScape connection when enabled. This can be problematic when trying to debug programs from a remote location. Serial communications can provide a solid connection to the PLC but lacks the versatility of Ethernet. Consider using Modbus protocol for inter PLC communications over Ethernet. Later revisions of Horner’s firmware allow PLCs to be setup in the hardware configuration as both master and slave units.

Siemens upgrade path from TP177 panels is to the TP700 Comfort panels. Siemens has decided to discontinue its Data Highway over RS422 protocol in this line of HMI panels and will not communicate using this method. There are two options to go from here, one can upgrade the Allen Bradley CPU to a SLC 5/05 with Ethernet or utilize the DF1 port on the SLC 5/03. If the latter option is chosen, Siemens provides an RS422/RS232 converter which will allow for communication.

Removable memory has always come with this concern: how do I know data isn’t being written onto the card when I try and remove it. If the PLC (or any computer) is writing to SDCard when it is being removed, there is a chance for file corruption. To resolve this issue, computer developers have come up with the concept of “unmounting”. Unmounting will prevent the PLC from writing anything else from the SDCard, allowing it to be removed from the PLC safely. To as a Horner PLC to safely unmount an SDCard, Horner provides system registers %SR174 and %SR175 to unmount and check the status respectively.

Horner PLCs allow for the HMI buttons to jump to a screen defined in a register. In the ladder logic, define two registers, one register can be setup one screen ahead of the current user screen (%SR1) and another register setup one screen behind. Buttons can then be copied and pasted to move between screens sequentially. The caveat to this is that it will break when trying to use Envision.