Comments (4)
I have a similar scenario with hundreds of devices connected to a server and what we do is instead of the 1 byte heartbeat, we pass a simple modbus package with a function code that means heartbeat (out of the defined ones in the standard). This translates to about a minimum of 6 bytes instead of 1. For my scenario it's fine because the heartbeat occurs every 5 minutes or so (I more or less trust the TCP session over GPRS).
If you want to keep that 1 byte heartbeat, I can copy the implementation of the maxDataInterval
option in the serial transport. What it does is define a maximum time between data. If that time is reached, the current buffer is interpreted and then discarded.
What's the frequency of the heartbeat?
from stream.
https://github.com/node-modbus/stream/blob/master/lib/transport/serial.js#L49-L53
from stream.
The heartbeat frequency is 1 minute from last sent message (heartbeat, ReadHoldingRegisters,...) We know from experience that Amazon/Azure close idle connections after 4 minutes or less.
Your first solution in which devices send periodically modbus-response like heartbeat is better. I didn't know that I could do that. We've done that and works fine.
Thank you very much
from stream.
Glad it worked 😃
from stream.
Related Issues (20)
- Error on install
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from stream.