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dexta

PLC/ HMI serial port interface

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Good Day

Wondering if someone can shed some light if PLC/HMI serial port connection can be done with weight scale using serial port ( RS232)

Currently using Fanuc 90-30 with Pro-Fae HMI but can adapt.

 

THank you kindly

Peter

 

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I think you should post this in the GE Forum.  Steve Bailey is an expert.  If he doesn't know the answer, I'm sure he knows someone that does.

Personally, I've done it thru the serial port of a Rockwell MicroLogix.  Add code to scan for characters in the buffer.  Confirm correct length.  Then move the data and store in another location for additional logic and eventual display on HMI.

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It is possible, but the devil is in the details.

You will need to know the details of how the weigh scale interfaces to the world through it's serial port. Some can be set up to transmit the current weight periodically. Some will  only respond to requests from an external device like a PLC. On the 90-30 side, a lot depends on which hardware you're using. Some 90-30 CPU models have built-in serial ports that can be controlled from the ladder logic. In the absence of a CPU like that, there is the possibility to add a serial communications module or a Basic language programmable module with serial ports. 

So for starters, what is the brand and model number of the weigh scale? How is the Proface HMI connected to the PLC? What PLC CPU model are you using? Are there spare I/O slots available in case you need to add a module?

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Good day

the system config is the following

350 CPU

311cmm

couple of i/o modules

Pro-Facec Gp2301 HMI ( pendant ) connected via rs-232 on the CMM311

THe scale is Ohaus Defender ( I found an article about interfacing : https://www.digitalscalesblog.com/tag/ohaus/)

 

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I think you're going to have to change to a CPU model with serial ports. You have a second serial port on the CMM311 module, but it is limited to SNP, CCM , and RTU protocols, none of which appear to be available on the scale. If you can get your hands on a CPU with a serial port (CPU351, CPU352, CPU363), there is sample ladder logic in the manual GFK-0582D for setting up the port to receive serial data.

Another possibility could be if there is a second serial port on the HMI and if you can write a script in the HMI to handle serial port communications.

 

 

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Good day

Thank you for all the precious info, looks like 90-30 is not too serial friendly. Checked with Pro-face, there is a scripting feature which looks friendlier than the ladder code.. Will give that a crack.. .

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If your HMI has two serial ports and its scripting language has decent string handling capabilities, that's the easiest way to get it done. Read the characters from the serial port as a string, extract the number from the string and write it to a PLC variable.

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