NEC IE-784000-R, User Manual

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CHAPTER 8 FUNCTIONS OF RESPECTIVE CHANNELS
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(4) Handshake mode
Hardware handshaking is established by connecting handshake signals RTS, CTS, DSR, and DTR. If these
signals are not connected, software handshaking is executed. Usually, channel 1 executes both hardware
handshaking and software handshaking simultaneously to transfer data.
Hardware handshaking is to transfer data 1 byte at a time by using a handshake signal. This is called character
handshaking. Software handshaking cannot handshake on a byte-by-byte basis, but can handshake on a block
basis. This is called flow control.
The IE-784000-R automatically adjusts its hardware by using the respective handshake signals so that no data
overlap during handshaking. For example, if a buffer becomes full, the IE-784000-R controls the CTS signal and
completely stops data transfer. Therefore, no data is skipped as long as the handshake signals are connected.
If the handshake signals are not connected, however, only software handshaking is executed, and there is a
possibility that some data are skipped.
(5) Character specifications
The character specifications for data transmission/reception are as follows:
– Character length
Fixed to 8 bits
– Parity bit
None
– Stop bit length
Fixed to 2 bits