cheapest robust way to convert an ascii string serial to modbus tcp relay closure.

[ganutenator]

Found an awesome point of sale for $500.
It sends an ascii string when a product is sold.
Need to convert this into a number between 0 and 255 or less and send this via modbus tcp/ip.

i'm thinking grid connect product.

then thinking twio like product (obsolete) converts this modbus tcp/ip message and fires relays.

Any suggestions?

 

[damica1]

Can you program what the ascii string is? If you can, just use the ascii chart (I have attached a picture) send out a decimal 49 = 1, 50 = 2, 51 = 3 and so forth. Then just use "ascii to int" function to convert the string. Now onced product A is sold POS will send (Decimal 49) if product B is sold POS will send out (Decimal 50).

If your not looking for a certain ascii string but just need a "High or Low" signal when product is sold, most POS system have the means of pulling a RS232 pin high this would be done in their setup configuration.

There is a lot of things going on with a POS system. Most won't send out RS232 information until end of transaction, but you might be able to use the "Customer Display" RS232 because it is designed to send information out everytime a Product is added to sale. If you just need to know everytime the transaction is complete then use the "Drawer Release" signal. This would actually fire a 12vdc signal for about 250ms.

I hope this helps.