Re^2: Lost characters using Device::Modem

jbert:

I totally agree with you--you should use flow control whenever possible. Unfortunately, it's not always possible. In order to implement flow control, all devices in the chain must support it. It's not uncommon in the embedded world to connect with things that have no flow control. You may just have minimum/maximum timings on a specification sheet.

For example, let's suppose that the modem on the SMS system, once it gets the proper "doit" string from the originator triggers a relay that connects the modem to a transmitter. That relay could take a few milliseconds to engage, and you could easily lose the first character or two while the relay is actuating.

--roboticus

Comment on Re^2: Lost characters using Device::Modem

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Re^3: Lost characters using Device::Modem by jbert (Priest) on Nov 26, 2006 at 19:34 UTC
Oh, agreed. If you're talking to a device which won't play ball with flow control, you don't have much choice. But, as you say, hopefully you then have a spec sheet and can put in the "theoretically correct" delays and timings, or something close.	[reply]