HP 24SII - Manual (Page 70)


 

  
 

   
BETWEEN COMPUTER AND PERIPHERAL THROUGH MODEL
24SII
When a computer transmits data to a peripheral device through a
computer port on the Model 24SII DES, the data is received and
stored in the spooling buffer (standard 1MB; optional up to 16MB)
which in turn retransmits it to a peripheral device through a printer
port. During transmission, when the buffer fills, the Model 24SII DES
will make the computer port's DTR (Data Terminal Ready) line low
(negative voltage), signaling the transmitting computer that it cannot
accept more data.
When the Model 24SII DES retransmits the data to the peripheral
device through a printer port, and the peripheral device cannot receive
any more data, the Model 24SII DES will expect to see a low on the
CTS (Clear-to-Send) line. When the peripheral device can receive
more data, the Model 24SII DES will expect to see a high on the CTS
line.
When the buffer of the Model 24SII DES can receive more data, the
Model 24SII DES will make the transmitting computer port's DTR line
high (positive voltage).
In the reverse direction (peripheral-to-Model 24SII DES-to computer),
handshaking is the same, but the spooling buffer is not utilized.