RSView32, tag values

I have two applications on two pc's 40ft apart, they are identical except for the fact they are logging the data to different locations on the network, the tags are the same, but they are displaying different values, I have never noticed it until today, not that its a major issue but, I thought it was strange, any ideas why or what would cause this?

one reads 510 deg f and the other reads 513 deg f....this node is over DH+

Thanks

Scaling? Offsets? Overlaps in copying data for transfer? How is the data prepared for transfer and received?

Are these integers? The difference between 510 and 513 is significant. Look at the two numbers in binary form and you'll see what I mean. Has to be something overwriting the value.

Hey Tim,

Thats what I would of thought but... I ghosted the images myself, I only change the data logs and a .bat file when I change out one of the pc's, I just copied the program and verified it.

check your e-mail, look at tags N15:6-N15:9 they are just straight displays

geniusintraining,

My educated guess is that it may be heat loss over the DH+ network.

My uneducated guess is I don't have the slightest ideal what could cause this.

Quick guess:
There is a little bit of noise in the wiring from the temperature sensor to the PLC, the reading is jumping a couple of degrees up and down. Mean while, the two PC's are polling at the same rate, but not exactly at the same time. PC1 reads the value when it's jumping up, PC2 reads the value when it's jumping down.

You can rationalize anything, if you take a big enough leap in faith

I agree with Ken on this one. Unless your logging rate is short and the computer times sync'ed together you will see some inconsistencies especially on analog values that are ever changing when using the datalog function of RSView.

Thanks guys

Just check the scan class is set up for 1 sec foreground and 5 sec back ground, I looked at the value of the tag and it does not seem to be fluctuating, but you never know, just thought it was odd.

Thanks again

GIT,

I noticed this phenomonon several years ago. Thes system had two PC's, each running their own copy of RSView32, but reading exact same tags from the same SLC 5/04. There were a bunch of thermocouples measuring a gas furnace. Some of the temperature trends on the two monitors never quite agreed exactly, but were close. I decided that it was indeed due to the fact that the PC's were getting the data at different times. Later I nullified the differences by changing the worst cases to read average temperatures, accumulated in the PLC for some small time period, say 5 seconds. Then, both monitors were usually looking at the same data, even though at slightly different times.

Finally got to take a quick look through the program. Don't see anything to cause the change. I'll take a second look when I have more time. Going to have to agree with what has already been stated. Know you said it was no big deal, so when you have time maybe you could scope the actual signal for fluctuation.

Thanks guy's,

Good idea Lance I think that would solve the differences, thanks for looking TW

Ken very good quick guess, just think of what you could do if you took your time

thanks