505 SFPGM Question

Was looking through some old PLC code I was given 10 years ago to find out how to change the action of a loop in Tisoft.

The SFPGM code uses some syntax that I cant find in the reference manual - can anyone help

The code is

IMATH LCFH1 := LCFH1 ^ K94 (where K94 is a binary word with bit 8 on 0000 0000 0000 1000 0000)

that makes the loop go direct acting (turns that bit OFF)

the other piece says

IMATH LCFH1 := LCFH1 | K94

which turns that bit ON

I know it works - I tested it - but I just want to make certain of the syntax and of possible find the manual that it comes from.

Thanks

Jason

LCFH is the Loop C Flags High Word, so you are manipulating the 8 bit of loop 1's high word. The 8th bit sets the loop to reverse or direct acting.


The "^ "indicates a WORD XOR, this shorthand entry is only supported in processors with power math. In the older platforms it would have been entered as WXOR.

The "|" indicates a WORD OR, also shorthand, in the older platforms you would have to use WOR.





So in the first statement, since the bit is on, and the eighth bit of K94 is also on, the XOR returns a zero, and the bit goes to zero.
In the second statement, since K94's eighth bit is true, the loop bit is set to one.

Thanks Ken

I found that table OK in the 505 reference manual bu t the bit where it showed the caret and pipe wasnyt in there

All clear now

Cheers

Jason

Jason

The table is in the Programming Reference manual, Table 7-5 "IMATH Operators", page 7-42.

I think the first piece of code may cause the mode to toggle, eg:
if mode bit is 1: 1 XOR 1 = 0
(changes from Reverse to Direct acting)
if mode bit is 0: 0 XOR 1 = 1
(changes from Direct to Reverse acting)

The second piece of code should put the loop in Reverse Acting mode.
If you want to put the loop in Direct Acting mode you could try: IMATH LCFH1 := LCFH1 &(NOT K94)
- "&" is the Bit-by-bit AND of two integers

Cheers for that Phil

I had worked out what was going on using the XOR function - but nowhere could I find reference to the fact that ^ and | were used in SFPGM code.

Table 7.5 in my TI505 reference doesnt have those characters. It does have WOR and WXOR but not those 2 characters as shortcuts.

I used TICON to convert the program and wondered if somehow the syntax had become corrupted.

But its all clear now.

Thanks

Jason

You can download the same manual that I have here:
http://support.automation.siemens.com/US/view/en/1936751

Cheers Phil

That one was the Fifth edition - I had the Second edition - bit of a difference there.

Jason