Sergei Troizky

 I've used such combination many times.  However, it's necessary to see both your connection diagram and the PLC code.  PM me if you do not want to post them.

It is indexed addressing. The index register V or Z signed value is being added to directly specified value, which creates the final address. Examples: D500Z means D500 when Z=0, or D510 when Z=10, or D400 when Z=-100.  The resulting address must be within valid range for the PLC.

From my experience, word data type determines only the value range, for monitoring and value set from external device (e.g. PC). It does not affect the way the symbol is processed by the program. If signed 16-bit is sufficient for you, assign CHANNEL type to word data. 

Be aware, that on some PLC models "memory extension card" does not add to existing memory, but replaces it.

 Memory word 81 is not A81. This is an absolute address in PLC memory. Here you are. Reading word 81: Simpler than I imagined. Be aware, though, that memory word 81 is written on PLC power up and reflects the PLC mode on power up. It does not necessarily indicate the actual mode at any moment and you will not see any changes when switching the powered PLC mode. 

This is highly unlike to be doable programatically. I would say "impossible", but never say "never". What is the goal?

If a PLC is equipped with real time clock, store actual date/time permanently in holding registers. In first scan calculate the difference between actual date/time and stored values. This difference is the PLC Off time.

X18 input address is illegal in Mitsubishi. Inputs/outputs addresses are octal, hence cannot contain digits 8 and 9.

I have to translate several similar diagnostic screen messages "Device A not clear for Device B". "Not clear" may mean any of the following: - Device A position is unknown and may be not clear for Device B motion. - Device A position is known and is not clear for Device B motion. How should the message be translated into French in most compact form? The translation does not have to be literal, but reflect the meaning best. Any suggestions are highly appreciated.

Thank you, Armadillo852 The issue is resolved.

Mostly, but I also expect little better scantime with ML, and you will have low-cost high-speed capabilities should you need them. Be careful however, and ensure that the ML analog input and termocouple module specifications meet your needs. Also, it will be more expansion modules with ML, as they are mostly 8-point, except digital I/O 16-point ones.

 Well, I would put two ML1400 on Ethernet network.

You mentioned AC inputs twice. Was this a mistake? Did you mean AC outputs in one instance? It still may be possible with ML1400. Do not forget, that unlike SLC, you will get 20I/12O and 4AI on the main unit. Or, put two ML1400 units on the Ethernet network, along with HMI(s) and programming PC.

 Most probably, these bits are written by the operator interface display.

I strongly recommend to consider ML1100 or ML1400. Both have on-board Ethernet port and online-editing (which is not available in ML1500). 

Early OS versions of SLC5/03 did not support online editing, indirect addressing and floating point.

Do not have CJ1 to try, but in CP1 any non-holding coil driven by P_On (Always On) contact does the job.

 PMCR, I am interested too, for CP1 if there is difference. Could you PM me too? P.S. Just out of curiosity, if you are ready to share a solution, why don't you post it instead of sending to each interested?

Handshaking is signal exchange between two pieces of equipment, in order to synchronize processes in both.

Neither procedure. Your result is of reasonable accuracy. Just for reference, 7 significant decimal digits allow to measure: - Tens of kilometers in cantimeters (well, tens of miles in inches), or - Tonnes in gramms, or - Couple hours of time in milliseconds, or - Over 3 months of time in seconds. And remember, floating point format is not for counter (which must correctly add single units even close to limit values), but for reasonable accuracy calculations.

The precision of single-precision floating point format is 23 bits of mantissa, which means 7-8 decimal significant number. Being applied to your example, this means you can trust the 15.62500 part only, and should ignore the rest.

It is still unclear WHAT you need to do, so cannot advice you HOW. Clarify the task and specify your PLC model. And what do you mean by Output #9 in Mitsubishi?  

You did not specify the PLC class and the comparison criteria. There is no such thing as just the best PLC, like there is no the best tool, vehicle, weapon, woman, etc.

Not really that simple. As the division result is fractional, you should decide, how many decimal positions you need in the result. Then you should decide whether truncating after this decimal is OK or you need mathematically correct rounding, in which case the latter must be programmed additionally. The calculations themselves may be done in either integers or floating.

I would create a 0.5ms timer interrupt (the fastest possible in this PLC), refresh and process these inputs by regular ladder within this interrupt. But probably, the best is to replace the 1/6 metal targets with 50/50 ones.