What shall we send in SwVersion, what is the purpose of this field?
The hello message is optional. It is our experience that certain GPRS modems, for example the GT47 from m2mconnectivity, do not reliably indicate to the RS232 attached device that an established TCP socket has been closed by the remote end or network. This means the vending device does not learn about the connection failure until after a send is attempted. If this a send containing a transaction, a very long period (>14 seconds) may be needed for the device to re-establish connectivity. This would be unsatisfactory for the cardholder. DPS would recommend periodic sending of a hello message by the vending device to check that connectivity is available every 30-60 minutes or so. If a hello message fails (no response received), the device can reset the modem as needed. The contents of this message are such as Version etc can be used for optional features such as new firmware downloading – in this scenario the DPS host can detect a software version of an installed vending device and make a
