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Troubleshooting & Repair Teledyne API - Model T200H/T200M Operation Manual
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7.5.12. RS-232 COMMUNICATION
7.5.12.1. General RS-232 Troubleshooting
Teledyne API 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 API conforms 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 Section
4.11.5 for connector and pin-out information.
The communications (baud) rate and protocol parameters are incorrectly
configured. See Section 4.11.3.2 on how to set the baud rate.
The COM port communications mode is set incorrectly (Section 6.11.8).
If a modem is used, additional configuration and wiring rules must be observed.
See Section 6.15.2.6.
Incorrect setting of the DTE - DCE switch. Typically, the red LED is on as soon as
you power up the analyzer. If not, contact the factory, as this indicates a problem
with the motherboard. As the analyzer is connected to the computer with a cable,
the green LED should also illuminate. If not, set the DCE/DTE switch to the other
position. See also Section 6.11.5.
that some laptops do not enable their RS-232 port when in power-saving mode. In
this case, connect the laptop and start either APICOM or a Hyperterminal window
and start communicating with the analyzer. This will enable the serial port on the
laptop and the green LED should illuminate. You may have to switch back and forth
while communicating to get the right setting.
7.5.12.2. Modem or Terminal Operation
These are the general steps for troubleshooting problems with a modem connected to a
Teledyne API analyzer.
Check cables for proper connection to the modem, terminal or computer.
Check the correct position of the DTE/DCE as described in Section 6.11.5.
Check the correct setup command (Section 6.15.2.6).
Verify that the Ready to Send (RTS) signal is at logic high. The T200H/M sets 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 6.15.2.6 and 6.11.8.
Use the RS-232 test function to send “w” characters to the modem, terminal or
computer; See Section 6.11.10.
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.
Make sure that the communications software is functioning properly.
Further help with serial communications is available in a separate manual “RS-232
Manual”, Teledyne API part number 013500000, available online at
http://www.Teledyne-api.com/manuals/.
07270B DCN6512