I have an LS300 connected to a PLC via Serial RS232. I am bring in (4) 16Bit words in every minute from a remote server. For some reason, the data usage on the cellular network is over 1Meg/Day. If I look at wire shark, the length of data per poll is around 259. Why is it so High?
Don’t forget that there are 8 bytes of framing info around every packet of data that you send.
So … if you are receiving 8 bytes (your 4 16 bit words), the packet is going to be at a minimum 16 bytes long.
24 hours = 1440 minutes = 23040 bytes (approx 22.5 kbytes) - which sounds pretty good.
Depending on your ISP’s plans, you may be being charged not by the byte, but by the block - and I’ve seen some ISPs charge by rounding up to the nearest 1k block of data. This is especially true when the GPRS connection is being set-up/torn down on a regular basis (so you’ve also got the additional traffic for set-up/tear-down). If you are being charged by the minimum 1k block, then I suspect that you would be seeing about 1.5Mbyte per day:
1440 minutes x 1k = 1.4Mbyte
Additionally, the device may also be talking to the network for other things. I know the GX400’s used to talk to the network for things like NTP time info etc and had a fixed data usage per day.
Have a look at your data plans and see how you’re being charged.
Or, the device could be padding your data to completely fill the packet (around 1492 bytes).
Just my 2c.