s7 300 a basic question

hi all,

the program segment in stl is as follows

network1:

1. a m 0.0
2. jc l1
3. a m0.1
4. jc l2


m0.0 =0

m0.1 =1

i don't know:

1.the value of rlo before step 1
2.the vaue of rlo after each step

hlp aprctd

thnx

if m0.0 is true then jump to label l1, otherwise if m0.1 is true jump ot label l2...

thnx turpourpo

m0.0 = 0
m0.1 = 1

these values exist before the start of network 1

i'm confused beacause i think that after executing step 1 the RLO becomes 0.
so at step 3 and thereafter RLO remains at 0 until some set or or instruction.
but i know that this is wrong but where?

thnx agn

If M0.1 is true then at Step 3 the RLO will become 1

hi ld,
as mentioned m0.1 is 1

"A checks whether the state of the addressed bit is "1", and ANDs the test result with the RLO.":-stl programming manual

the value of RLO at/after step 2 is 0 then as per the def cited above the value after step 3. should remain 0 even if m0.1 is 1

also what is the value of RLO at the start of a network.i think it should be 1 irrespective of the value at the end of previous network, if the analogy of a network in stl is a rung in lad and the power rail is the start point of a rung.

there is a fault in my understanding but where?

thnx agn

Read up on the first check, /FC

hi ld,
i tried my best but still could not get any info on /fc other than

"* Bit cannot be evaluated in the user program with the L STW
instruction since it is not updated at program runtime."

but i think the answer to my question lies in

definition of jc

"If the result of logic operation is 0, the jump is not executed. The RLO is set to 1, and the program scan continues with the next statement.":stl programming manual

so at step 3 the RLO starts with 1;

anyway i would be grateful if you will share any info that you have on /fc

thnx

From the block editor use Help on statement list:

many thnx ld,

my folly