Communications - Teledyne T802 Operation Manual

Troubleshooting and Service
11.6.11. RS-232 COMMUNICATIONS
11.6.11.1. GENERAL RS-232 TROUBLESHOOTING
11.6.11.2. TROUBLESHOOTING ANALYZER/MODEM OR TERMINAL OPERATION
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Teledyne API T802 Paramagnetic O
Teledyne API analyzers use the RS-232 communications protocol to allow the
instrument to be connected to a variety of computer-based equipment. RS-232
has been used for many years and as equipment has become more advanced,
connections between various types of hardware have become increasingly
difficult. Generally, every manufacturer observes the signal and timing
requirements of the protocol very carefully.
Problems with RS-232 connections usually center around four general areas:
1. Incorrect cabling and connectors. See Section 3.3.1.8 for connector and pin-
out information.
2. The BAUD rate and protocol are incorrectly configured. See Section 6.2.2.
3. If a modem is being used, additional configuration and wiring rules must be
observed. See Section 8.3
4. Incorrect setting of the DTE – DCE switch is set correctly. See Section 6.1.
5. Verify that cable (03596) that connects the serial COM ports of the CPU to
J12 of the motherboard is properly seated
These are the general steps for troubleshooting problems with a modem
connected to a Teledyne API analyzer.
1. Check cables for proper connection to the modem, terminal or computer.
2. Check to make sure the DTE-DCE is in the correct position as described in
Section 6.1.
3. Check to make sure the set up command is correct (See Section 8.3)
4. Verify that the Ready to Send (RTS) signal is at logic high. The T802 sets
pin 7 (RTS) to greater than 3 volts to enable modem transmission.
5. Make sure the BAUD rate, word length, and stop bit settings between modem
and analyzer match, See Section 8.3.
6. Use the RS-232 test function to send "w" characters to the modem, terminal
or computer; See Section 8.3.
7. Get your terminal, modem or computer to transmit data to the analyzer
(holding down the space bar is one way); the green LED should flicker as the
instrument is receiving data.
8. Make sure that the communications software or terminal emulation software
is functioning properly.
Further help with serial communications is available in a separate manual "RS-
232 Programming Notes" Teledyne API PN 013500000.
Analyzer Operation Manual
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07275B DCN6418