This function reads the driver's interface record and copies it into the buffer passed by the SNALink. The buffer must be allocated by the SNALink prior to making this call.
The interface record format is as follows:
Description | Type |
---|---|
Received Frames | int |
Transmit Buffer Space | int |
Status Events | int |
Input V.24 Status | UCHAR |
Output V.24 Status | UCHAR |
Statistics Counters | int[11] |
Whether more frames can be provided to the driver.
Whether the driver still has frames waiting to be sent.
The Transmit Buffer Space field indicates the maximum frame size that the driver can currently accept. This is updated after each successful Transmit Frame IOCTL, and should be checked by the SNALink before sending further frames to the driver.
Bit number |
V.24 circuit name | Circuit number |
RS-232C pin |
---|---|---|---|
7 - 5 | Reserved | 142 | 25 |
4 | Test Indicator | 125 | 22 |
3 | Calling Indicator | 125 | 22 |
2 | RLSD (commonly DCD) | 109 | 8 |
1 | Data Set Ready (DSR) | 107 | 6 |
0 | Ready For Sending (CTS) | 106 | 5 |
Bit number |
V.24 circuit name | Circuit number |
RS-232C pin |
---|---|---|---|
7 - 5 | Reserved | ||
4 | Maintenance Test | 140 | 18 |
3 | Select Standby | 116 | 11 |
2 | Data Signal Rate Selector | 111 | 23 |
1 | Data Terminal Ready (DTR) | 108/2 | 22 |
0 | Request to Send (RTS) | 105 | 4 |
Note that the driver will raise and lower RTS as necessary while transmitting, reflecting the state of RTS in the output V.24 status field. The application should not, therefore, try to manipulate RTS.
Counter 1 | Frames received with incorrect CRC. |
Counter 2 | Frames larger than the maximum size received. |
Counter 3 | Frames smaller than 32 bits received. |
Counter 4 | Frames received that are not a multiple of 8 bits. |
Counter 5 | Aborted frames received. |
Counter 6 | Transmitter underruns. |
Counter 7 | Receiver overruns. |
Counter 8 | RLSD drops in mid-reception. |
Counter 9 | CTS drops in mid-transmission. |
Counter 10 | DSR drops. |
Counter 11 | Hardware failures (adapter or modem). |
The interface record provides a fast mechanism to use to decide whether a frame can be transmitted, whether there are any frames to be received, and so on. The driver maintains this information. Each time the SNALink requires this information, it calls Read Interface Record to get a copy of the current interface record. After each call, the driver clears the statistics counters in its own interface record. The V.24 status and transmit and receive data information are unchanged.