Communication; General Rs-232 Troubleshooting; Modem Or Terminal Operation - Teledyne T101 Operation Manual

Teledyne ML - T101 Operation Manual
9.5.11. RS-232 COMMUNICATION

9.5.11.1. General RS-232 Troubleshooting

9.5.11.2. Modem or Terminal Operation

For complete failures, assuming that the power supplies are operating properly and the
wiring is intact, the CPU is faulty if on power-on, the watchdog LED on the
motherboard is not flashing.
In some rare circumstances, this failure may be caused by a bad IC on the motherboard,
specifically U57, the large 44 pin device on the lower right hand side of the board. If this
is true, removing U57 from its socket will allow the instrument to start up but the
measurements will be invalid.
If the analyzer stops during initialization (the front panel display shows a fault or
warning message), it is likely that the DOM, the firmware or the configuration and data
files have been corrupted.
Teledyne ML analyzers use the RS-232 protocol as the standard, serial communications
protocol. RS-232 is a versatile standard, which has been used for many years but, at
times, is difficult to configure. Teledyne ML instruments conform to the standard pin
assignments in the implementation of RS-232. Problems with RS-232 connections
usually center around 4 general areas:
Incorrect cabling and connectors. This is the most common problem. See
•
Figure 4-8 for connector and pin-out information and Section 4.7.3.
The communications (baud) rate and protocol parameters are incorrectly
•
configured. See Section 4.7.11 on how to set the baud rate.
The COM port communications mode is set incorrectly (Section 4.7.10).
•
If a modem is used, additional configuration and wiring rules must be
•
observed. See Section 5.1.2.7.
• Incorrect setting of the DTE - DCE Switch is set correctly See Section
4.7.5.
These are the general steps for troubleshooting problems with a modem connected to a
Teledyne ML analyzer.
Check cables for proper connection to the modem, terminal or computer.
•
Check the correct position of the DTE/DCE as described in Section 4.7.5.
•
Check the correct setup command (Section 5.1.2.7).
•
Verify that the Ready to Send (RTS) signal is at logic high. The T101 sets
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pin 7 (RTS) to greater than 3 volts to enable modem transmission.
Make sure the baud rate, word length, and stop bit settings between
•
modem and analyzer match, see Section 5.1.2.7 and Section 4.7.
Use the RS-232 test function to send "w" characters to the modem,
•
terminal or computer; See Section 4.7.10.
Get your terminal, modem or computer to transmit data to the analyzer
•
(holding down the space bar is one way). The green LED on the rear
panel should flicker as the instrument is receiving data.
Troubleshooting & Service
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