Troubleshooting an RS-232 connection
For troubleshooting an RS-232 connection (a direct connection to the PC from a NetClock Time Server / Master Clock serial port or the use of a TimeTap connected to the remote port), a laptop PC with HyperTerminal or ProComm installed is required. A standard RS-232 cable pinned straight through may also be required. Instructions on making a cable with the minimum pin connections are given in the UNIX time synchronization using RS-232 section.
To verify the RS-232 connection has a proper output, connect it to the serial port of a laptop computer. This procedure is also valid if using a TimeTap including model 8178T, as well as the model 8179T (a standard DB9 to DB25 adapter may be required with older model, 8178T). If using a standard RS-232 pin-out, the jumpers on the 8178T and 8179T, and the external power supply for the 8179T are not required during this test because the PC provides flow control and power to the TimeTap.
Using the terminal emulator screen, you should see a line on your screen every second that looks similar to one of the two samples below (depends on selected Data Format from the Time Server or Master Clock).
306 13:23 STZ=05 (Data Format 0)
99 315 18:36:14.267S (Data Format 2)
If the PC is connected to a serial port on the Time Server / Master Clock, and the port is configured for interrogation mode, then no line will be present. You need to type an uppercase T to query the Time Server / Master Clock. Any other character will respond with a "*".
| Test Result |
Problem |
Solution |
| ASCII line is present and readable on the test PC |
Cable problem between the UNIX PC and time server / master clock
Problem with client s/w on PC |
Check the cable used with the UNIX PC
Check + NTP resources for assistance |
| ASCII line is present but not readable (Unreadable data that is present every second) |
RS-485 lines are backwards on the TimeTap, + Data and - Data lines are flipped |
Reverse the leads and repeat the test to verify the lines of data should now be readable |
| ASCII line is not present |
Check the settings of the terminal emulator (such as baud rate)
Cable problem |
Correct settings
Verify pinout of the cable and try a loopback test - see below |
| "?" or "*" at the beginning of the line |
The Time Server or Master Clock is not time synced |
contact Spectracom tech support for assistance |
| * is returned when interrogated |
not interrogating with uppercase T |
Type uppercase T |
Loopback test
Jumper pins 2 and 3 together on the cable and then on the PC Com port (One at a time) and press any character key on the keyboard. Whatever character is depressed should show on the monitor. If it doesn't show when pins 2 and 3 are jumpered on the test PC, the PC Com port is bad.