Automation Direct Click decisions.

[Tharon]

I'm thinking of upgrading a very old Sy/Max 100 to a Click, and am trying to do it as cheap as possible. Looking through Click options, I see there is a Basic CPU, and a Standard, the Basic not having a battery backup.

C0-00AR-D no Battery Backup
C0-01AR-D w/ Battery Backup

While not a huge difference in price, it'll be almost 43 dollars with the upgrade and the battery. I'm trying to figure out if I really need the battery backup.

I understand the actual PLC program is stored in non-volatile memory, so I won't lose that. But what about timer instructions? Will they lose their set values if it's powered down longer than the super capacitor can support? I plan on having a dozen or so timers, and four of them will have adjustable times set from a C-more Micro. Any advice? Thanks.

 

[Lancie1]

Yes, I think timer preset values will be lost after "a few days". This lost data will be reinitialized automatically, but to WHAT (0 or values in the program) we are not told - one of those mysteries that the great CLICK designer god chose not to share. I suspect that it reads initial timer values from the stored program, so there will only be a problem if you have a "retentive" timer that is temporarily stopped then restarted during operation. In that case after a power failure or shutdown, the timer could be re-initialized to the wrong value.

The Basic CPU modules do not have a battery back-up, but they have a capacitor that will hold memory for a few days. The data in the SRAM is lost if the CLICK PLC is powered off for long enough for the capacitor to discharge. In this case, the CLICK PLC initializes the data in the SRAM automatically. This also applies to Standard and Analog CPU modules if a battery is not installed.

 

[Tharon]

No, I won't be using retentive timers. But I will be setting a few timers' set values to a INT address, which I'm guessing will be set to 0 if it is ever off for longer than the few days. While recoverable from the Cmore, it'd be an annoyance that I don't think they would care to have.

Just to be on the safe side I think I'm going to have to go with the Battery version.

Edit:
Hmm... I can set initial values to the addresses. I wonder if that would be a better bet. Set it to some useful standard value and if it ever does get reset at least it won't be a "0" and screw up anything. Or just compare the integers in question, and if they are 0, move a set value into them. I think I'll do that, and go with the non-battery version.

 

[Lancie1]

I think they left the question of the reset values unanswered or deeply hidden, knowing for most situations, the potential cost of the risk is greater than the cost of the battery.

Mark that down in your black book for use when you hear someone say "Automation Direct is always customer-focused and always provides complete details on every device."

 

[Tharon]

Ya. I have to two options bouncing in my head now and every time I think I've made the choice I second guess myself and go back to the other option.

I'll sleep on it, and decide then.

 

[Lancie1]

Here is a little more information from Chapter 2, page 2-6, Click User Manual. Any initial program and memory values are stored in Flash ROM, and not moved to the SRAM volatile memory until and except when the PLC loses capacitor power, or goes from PROGRAM to RUN. It seems that if you can ALWAYS live with the initial or beginning values stored in Flash ROM (not resulting from the PLC running but from the PLC program), then you do not need the battery.

All CLICK CPU modules have a non-volatile FLASH ROM to store the downloaded ladder program and project file. The FLASH ROM has a total of 136K words. These are broken down into 8K words for the ladder program and 128K words dedicated for the project file. The FLASH ROM will retain the ladder program even with power removed from the CPU module.

The CLICK CPU modules make use of data registers to store values and conditions that are used during program execution. This data is stored in the SRAM memory. It is volatile memory, but is backed up by a super capacitor. The super capacitor is a special type of capacitor that is designed to provide power to volatile memory like the SRAM when the power to the CPU is off. However, it will not back up the memory for an extended time. In the case of the CLICK PLC, the super capacitor will back up the SRAM for a few days after the power is shut off. Once the super capacitor is discharged, all data in the SRAM are cleared when the CLICK CPU is powered up the next time.

 

[bce123]

Mark that down in your black book for use when you hear someone say "Automation Direct is always customer-focused and always provides complete details on every device."

I am sure a quick call on Monday to ab tech support would clear this up and as they don't ship on sunday so it should not delay your project

 

[Tharon]

Oh, time's not an issue. The current controller is running, they just had a scare last week and I figured I could replace it for relatively cheap and in the process make it a little better, more customizable.

I'm sure I could get the answer from AD's tech support on Monday no problem.

 

[OkiePC]

You are talking like fifty bucks to move up to the top of the line...right? Real time clock, battery backup...

 

[Albert LaFrance]

Yes, going from Basic to Standard gets you not only the battery backup, but also the real-time clock AND an RS-485 comms port.

 

[Tharon]

You are talking like fifty bucks to move up to the top of the line...right? Real time clock, battery backup...

I'm not saying that the 50 bucks is overpriced for what it offers, just that it might be an unused upgrade if I spent the money on it. By choosing the basic unit, I can keep the total cost of supplies under 500USD.