There is nothing wrong with latches first of all, if the latches are in the non retentive area they will be reset on power up (check your documentation).
Keep latch & Unlatch on consecutive rungs if possible, there is nothing worse than set & resets in many places i.e. a single bit is set and reset many times.
Sometimes it is required to keep the state of latches even on power down & up.
It's just a matter of safety, if you don't feel safe using latches perhaps you shouldn't be doing the job. And if you do want to make any latches reset on power up (this can be to stop a sudden movement i.e. return of an actuator) then do it either on fist scan block or use a first scan bit at the start of the program or in the first block to be called. It is really that simple.
I had an argument some time ago, one guy said I never use latches (he meant step flags in reality), he always used registers i.e. sequence. I pointed out this is the same a register (if Retentive) will hold it's value
Keep latch & Unlatch on consecutive rungs if possible, there is nothing worse than set & resets in many places i.e. a single bit is set and reset many times.
Sometimes it is required to keep the state of latches even on power down & up.
It's just a matter of safety, if you don't feel safe using latches perhaps you shouldn't be doing the job. And if you do want to make any latches reset on power up (this can be to stop a sudden movement i.e. return of an actuator) then do it either on fist scan block or use a first scan bit at the start of the program or in the first block to be called. It is really that simple.
I had an argument some time ago, one guy said I never use latches (he meant step flags in reality), he always used registers i.e. sequence. I pointed out this is the same a register (if Retentive) will hold it's value