PLC or Traditional Relays

Hello everyone.

I am currently working as a member of an aerospace enterprise and am working on a ground station to communicate with our satellite. In the last station the team worked on they used a computer controlled relay board as a sort of intermediary between the umbilical that connects to everything inside the satellite and the ground station computer and the other objects used to test the satellite. I was recently asked to find out whether a PLC would be a better choice since it could be smaller and cheaper. When I looked up PLCs to buy I didn't really see any info on how much voltage or current they could handle which I think is my biggest concern. Other than that I welcome your input as to which is the better choice and suggestions as to what PLC would be the best choice.

The PLC would be transferring power to test the charging and discharging of the battery, other than that it would mostly be handling data going between the computer and satellite.

I'm pretty sure that a PLC is capable of this but I feel I should leave this in here as well. The ability to test charge or discharge on the battery needs to be done without changing any hardware around. The way this was handled before was to have the line connected to the battery in the umbilical pass through two relays so that it could be set to charge, discharge or neither but it was impossible for it to be both charging and discharging.

Well if any of you read through that mess of text I thank you for your help.


EDIT:
Once again I think a PLC is capable of handling this but I feel I should mention it anyway.

We plan on having this connected to a computer with a GUI so that the people running tests when we send it away just have to click a button and basically everything will be configured for the test they want to run.

The fact that "an aerospace enterprise" does not have a single controls engineer or a controls technician kind of scares me.

+1 LadderLogic

PLC I/O is generally designed to handle milliamp level signals. The exact amount depends entirely on the manufacturer and module selected. Some relay contact outputs are rated above 1 amp, but with limitations.
For anything requiring higher current output you will need to use an interposing relay to switch the higher current. This is generally a good idea anyway because an unexpected overcurrent will toast an inexpensive relay rather than an entire output module.

Like mendonsy says, every manufacturer is different.
https://www.automationdirect.com/clickplcs/index
Check out the above PLC.
You mentioned an HMI as well.
http://www.advancedhmi.com/
You can marry the above two together:
http://accautomation.ca/click-plc-advancedhmi-communication/

Hope this gives you some ideas.
Regards,

LadderLogic said:

The fact that "an aerospace enterprise" does not have a single controls engineer or a controls technician kind of scares me.

Click to expand...

I should have mentioned that this is a student led enterprise and by no means professional.

Thank you for clarification. It sounded like some defence-related place at first

check arduino, low power, and cheap.

briancr said:

+1 LadderLogic

Click to expand...

I don't quite follow which piece of his post this answers??

He was agreeing with this statement:

The fact that "an aerospace enterprise" does not have a single controls engineer or a controls technician kind of scares me.

Click to expand...

Before he knew that this was a student endeavour.

I agree with gclshortt, but he may be better off with a PAC platform. Consider the Productivity 2000 over the Click. Software is free. HMI communications would still be Modbus.