JSR vs MCP

In the AB PLC 5 what is the difference in using JSR's from the main program file to call other files and using the MCP to set the file scan order?

Is one more efficient than the other?

I have seen both used and both work well, but I perfer the MCP method to make the program a little cleaner...

Thanks in advance for your comments...

I just had this discussion with the engineer at our local rep.

Between each MCP there is an I/O update. There are times when you may want this, but is does lengthen the scan time.

With the JSR there aren't any, but it is not as clean.

He said some people make the mistake of doing both which will greatly increase scan time.

You can skip the IO update between MCP programs by setting the bits in S:78.

Understood...

msinclair said:

You can skip the IO update between MCP programs by setting the bits in S:78.

Click to expand...

That seems like the best of both worlds, if you want the program to only update the I/O once per program scan...

There are some applications, I think, where I want my I/O updated asap...

Thanks to you both...