SD Card Programming – Moderate

SD Card – Learn the basics

Downloads Vlp: sd-card

Questions /Answers

Q: are there any concerns with repetitive writing to an SD, like with the old EEPROM technologies?
A: there is a limit to the amount of times a specific bit can be writen to an sd card. I dont rembet the specific number but im sure it can be found online. It is relatively large for the task we are doing. But i guess this is a manufacturer specific spec.
Q: So it must be formatted using SD Card Suite, not the std Windows drive formatter?
A: we can do both. If we see taht the card is not seen in the PLC, we can use the WIndows tool first, to make sure the card is formated to the right file system.Q: Could discuss the 512b chunk on the Write Delimited Line function please?
A: the 512 byte limitation is due to teh way our controller writes blocks of data to the sd card. Everything is writen in 512 byte block, regardless of what function it is., If you see this as a limitation, ie, a string larger than 512 bytes, we can use two, three, as many as needed, functiosn to soter the correct sting. If this is of serious intrest to you.
Q: Anthony, can we get a copy of these program exaples?
A: Yes, this program and a recording of the webinar will be avalible a few days after teh webinar. This example is avalible in the examples folder of VisiLofic, Version 900–>SD–> V570 sd example

Q: Morning. but what about putting the sd in a pc. will it open or is it still protect
A: Glen, once the project is on the sd card, it can be copyied from the SD card. It can not be copyied to the SD with out the password.

Q: I have a customer that wants to password protect the sd card. i know that you can insert it in the v130 and pasword protect the card from upload and download but what happens if someone takes it out and puts it in a pc can it be opened or copied? xustomer does not want anyone to steal his program.
A: Hi Glen,the SD password FB will prevent some one from being able to copy the project to the SD card with otu havign the password.

Q: if it has a password can you still clone?
A: a password is required if you want to create a clone file from information mode of the PLC. no password is required to load/install the clone file from SD –> PLC

Q: What is the difference between the Rising Edge SB or just using a Positive Transition?
A: The SB 13 is the rising endge of SB 3, the 1 sec pulse (which has a duty cycle of 50%). THe answer is there is no difference between using a -|P|- of SB3 and a -| |- of SB 13, except we save on using a p contact. there are a limited amount of p contacts, and it is a nice thing the operating system is providing for us to have.

Q: can you format the card in the PLC
A: No, you NEED to format the Card froma PC. The PLC can only see the card after it has been formated,

Q: can you store the user program on the SD card and just update the system by inserting the card
A: Yes you can, we haev an HMI tool to help user do this, and we have ladder FBs that can automate this, as well as info mode tools to do this with. Jason will cover pgorams and clone files at the end of the presentation.

Q: Can the .csv files be read via a remote connection… via GSRM radio?
A: Hi David, i would liek a better understanding what you are trying to do before i answer yes, but in general, we can read back any of the information we have stored on the SD card in some manner. My hesitation in saying yes comes from the complexity it might requier to read back a file that does not have a tool to read it back. Meaning, we have a tool to read back Dt files on the SD card, we dont have a tool to read back .csv files, but we still have access to them, in an indirect manner.

Q: Can we access SD with SD Card Explorer over GPRS connection in Listen mode ?
A: Yes, GORS is listen mode is very similar to ethernet listen mode. The concern i would have is due to the potential size od the SD card files. It would probably not be recommended to transfer a large file from the SD card over GPRS. A better solution would be to use a 3G type cellular modem that comes with an ethernet switch and a controller with an ethernet card as the speeds will be much faster.

Q: can we create clone file without Upload capability ?
A: Uploading is different than downloading. We can create a program that is not uploadable, and make a clone file of it. We wont be able to do this from the PLC, but we can from the PLC.

Q: If you export the trend to Excel does it come in as data, graph, or both.
A: It comes as data. It can be graphed in excel.

Q: To insert or remove SD cards from the PLC should you have something in the program to stop stop writing to the card? If you don’t will it lock up the program or corrupt the files on the SD card?
A: We have a function block to “safety remove” card giving you a status bit.

Q: Most of my panels have high voltage in them. Opening the door brings lots of arc-flash liabilities. The SD card needs to be accessible from the front of the controller. Any plans of this? Or, possibly a 3rd party extension cable from the controllers SD slot to the panel door.
A: We dont currently have an option to change the access of the SD card. I am not sure what is in future development, but it has been requested by some users. There are SD card extension cables, but we generally do not recommend them as the bus of the SD card is not meant to be lengthened like this.