IBM SY44-5902-05 manual Concurrent LPDA-2 tests

This test displays five of the modem interface signals in a graphic format, showing the time relationship of the signals to each other.

Data Terminal Ready (DTR)

Data terminal equipment (DTE) uses this signal to show the modem that the DTE is ready to transmit and receive data.

Data Set Ready (DSR)

For nonswitched telephone lines, the active DSR signal shows that the modem is powered-on and ready to transmit and receive data. For switched telephone lines, the active DSR signal shows that the modem is connected to the telephone line and is ready to transmit data.

Request To Send (RTS)

DTE uses this signal to activate or deactivate the modem’s modulator lines. If the DSR signal is active, the RTS signal causes the modem to activate the carrier signal.

Ready For Sending (CTS)

The modem activates this signal in response to the Request To Send signal when the modem is ready to transmit data. When the CTS signal is active, the DTE can send data on the transmitted data line.

CTS delay is the time between the RTS signal active condition and the CTS signal active condition. On most nonswitched telephone line modems, there are three CTS delay options, ranging from 0 to 250 milliseconds (ms). Switched telephone line modems, operating in half-duplex mode, are normally set for 150 to 250 ms of CTS delay.

Carrier Detect (CD)

The modem uses this signal to show the DTE that the modem is receiving an acceptable carrier signal.

Because of hardware limits on taking short frame samples, the carrier detect signal might not be accurate. In this condition, an asterisk (*) takes the place of the sample data. The status is still correct.

Concurrent LPDA-2 tests

The purpose of these tests is to test the local and remote modems and get modem status information.

Test description

Use this option to run the Verify Link; it supports the LPDA-2 (VFYLNKLPDA) command. The concurrent LPDA-2 tests let you retrieve information from the data circuit-terminating equipment (DCEs). DCEs can be analog (modems) or digital (combined data service units (DSUs) and channel service units (CSUs)). You can get information from four tests:

vDCEs and line status

vDCEs and line test

vAnalyze line

vSend and receive test

You can run the LPDA-2 tests on a line while applications are using the line. The tests do not interrupt communications but temporarily slow the data transfer.

The following restrictions apply to these tests:

vThe DCEs must be compatible with LPDA-2.

Appendix A. OS/400 317