QPC513 Enhanced Serial Data Interface card Page 855 of 894
Circuit Card Description and Installation
Applications
The QPC513 Enhanced Serial Data Interface card is used any time that a
high-speed, fully synchronous serial data communication channel is needed.
The ESDI card is typically used to connect to the following:
• Meridian Mail
• A host computer using Meridian Link
• An auxiliary processor
The system processor transfers data to the ESDI card in blocks consisting of
1 to 128 eight-bit octets. Each block is processed in accordance with the
LAPB subset of the HDLC protocol and is transmitted serially to the output
port.
In receive mode, the EDSI card receives data serially from the input port
packages in LAPB information frames. After determining that the block is
error-free, the ESDI card supplies the data to the system processor as a block.
The ESDI card serial ports terminate on the card front panel. Figure 183 on
page 856 shows the typical ESDI card connections in a system.