Connect multiple Serial Interfaces to PLC
- Thread starter hein123
- Start date
briancr
Member
Multiple being how many?
What PLC? More info required
What PLC? More info required
Can't be done in any practical or cost-effective way.
Look for RS485 support on the scales or select other scales. With RS485 you can hook all of them up to the PLC.
It is very likely the scale has it. I have not encounter one that doesn't but I've only worked with industrial ones.
Of course ethernet connection will work too but will probably be more expensive as it would likely be an option in the scale.
Analog out might also work depending on the resolution/precision of the scales. But you'll need 40 analog inputs on the PLC. So more expensive.
.
Look for RS485 support on the scales or select other scales. With RS485 you can hook all of them up to the PLC.
It is very likely the scale has it. I have not encounter one that doesn't but I've only worked with industrial ones.
Of course ethernet connection will work too but will probably be more expensive as it would likely be an option in the scale.
Analog out might also work depending on the resolution/precision of the scales. But you'll need 40 analog inputs on the PLC. So more expensive.
.
Last edited:
Manglemender
Member
Could you get scales with an Ethernet connection and implement Socket comms?
Another option might be to use the Moxa serial to Ethernet devices, as mentioned previously, to a PC and write some code to grab the values and transfer to the PLC via an OPC server.
Nick
Edit:
This unit seems to support socket comms: http://www.moxa.com/product/NPort_5600-8-DT.htm
Another option might be to use the Moxa serial to Ethernet devices, as mentioned previously, to a PC and write some code to grab the values and transfer to the PLC via an OPC server.
Nick
Edit:
This unit seems to support socket comms: http://www.moxa.com/product/NPort_5600-8-DT.htm
Last edited:
briancr
Member
Why I asked what PLC, with AB go Flex IO and use 232 modules
A thought....
Not too expensive, what is your budget?
A thought....
Not too expensive, what is your budget?
FactoryTalktotheHand
Member
I've used Serial converters from Real-Time Automation. The435NBX series is made specifically for Allen-Bradley processors. You connect over ethernet and can have up to two serial devices per ethernet node. You configure the RTA to dump the data into a PLC address and monitor another PLC address for commands. It's pretty simple and straightforward, and the advantage is no complicated ASCII handshaking code in the PLC required. IF you're using A-B, that is.
harryting
Lifetime Supporting Member
I done similar thing with PLC5 and Contrologix with serial to ethernet converter (I used Prosoft but any of them should do)
One thing I ran into is the string to number conversion is memory intensive and I had almost ran out of memory issue on PLC5. When choosing your PLC, keep that in mind that you may need larger memory than you think you will need.
One thing I ran into is the string to number conversion is memory intensive and I had almost ran out of memory issue on PLC5. When choosing your PLC, keep that in mind that you may need larger memory than you think you will need.
BachPhi
Member
Real-Time Automation. 435NBX 40/2 = 20x $715 = $14300
JaxGTO
Member
Or even AB Point IO serial modules.
Firejo
Member
Cheap comes out expensive. If the scale only supports RS232 there’s a good chance that it is looking for a peer to peer connection which means it won’t be addressable. With that you can’t have 30 or 40 non-addressable devices on one network. Ethernet to serial converters could provide a solution in that the connection between the converter and the scale can be peer to peer with the converters having their own unique IP address which would be how you talk to each one individually. However that’s not going to be cheap. The other consideration would be to put a small Ethernet compatible PLC at each scale using it as the converter. That would give you a more “mainstream” system and you could have each PLC react to different situations (if the scale stops sending data you could send a notification to the host PLC for example).
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