What are some common problems and solutions when using the DS2155s internal HDLCs?
A7. The DS2155 SCT has the ability to transmit and receive packet data over a T1/E1 or J1 line. This device contains two high-level, data-link controllers (HDLC), each of which can be configured for use with time slots, Sa bits (E1 mode), or the FDL (T1 mode). Each controller has a 128-byte FIFO in the transmit and receive paths. The most common problems are receiving incorrect data in the packets, not receiving enough data bytes in the packets, or receiving a prematurely terminated (aborted) packet. Fortunately, for each controller, the DS2155 provides separate registers that contain information about any errors that occur when receiving data. These registers provide a basis for what action, if any, the system needs to perform for continuous normal operation. The HDLC registers provide information on the following receive packet conditions: In Progress, Packet OK, CRC Error, Abort, Overrun, and Message Too Short. The first condition, In Progress, means the HDLC is receiving a packet a
