Teledyne API Model 100AH SO2 Analyzer Instruction Manual, 02417, Rev. D
4.3.1.1 RS-232 Connection Examples
Example 1: Connecting the M100AH (using supplied cable) to an IBM-PC AT compatible
computer (DB-25 external connector, or DB-25 end of DB-9 to DB-25 Adapter).
In this case, the PC is wired as DTE and the analyzer is jumpers set as DCE, therefore a null
modem is not needed. The wiring is "straight through" i.e. pin 1 to pin 1, pin 2 to pin 2, etc.
Therefore all you have to do here is adapt the connector on the analyzer cable (male DB-25) to
the DB-25 male on the PC. A female to female DB-25 "gender changer" (cable or adapter) will
complete the connection. Make sure none of the adapters have null modems in them.
Example 2: Connecting the Teledyne API analyzer to a serial printer.
In this case, it will be necessary to determine whether the printer is DCE or DTE. Some printers
can be configured for either DCE or DTE by jumpers or DIP switch settings. Consult the user
manual for the printer. If the DB-25 connector pinout shows that data is output on pin 2 (from
the printer), then it is DTE and the TELEDYNE API analyzer should be switch set to DCE
mode. If pin 2 of the printer DB-25 is an input to the printer, then set the switch of the analyzer
to DTE mode. Refer to drawing #01916.
Example 3: Connecting the Teledyne API analyzer to a modem.
The modem is always configured as DCE. Therefore, setting switch as the DTE will be required
to connect the analyzer to the modem. Refer to drawing #01916.
4.3.1.2 RS-232 Diagnostic Procedures
There are several features of the M100AH to make connecting to RS-232 and diagnosing RS-
232 faults easier.
There are two LED's on the rear panel Connector Board that which are connected to pin 2 and 3
of the DB-9 connector on the board. If the switch is in the DCE position (default) the red LED is
connected to pin 3 of the DB-9 connector. When data is transmitted by the M100AH the red
LED will flicker, indicating data present on this line. When the M100AH is running, the LED
will normally be ON, indicating logic low. A one second burst of data can be transmitted over
the port by a command in the DIAGNOSTIC menu. Press SETUP-DIAG, scroll to select RS232
and press ENTR to transmit a burst of lower case "w"'s.
The green LED is connected to pin 2. If the switch is in the default DCE position, this is the pin
on which the M100AH receives data. It is ON if an outside device is connected. This LED gets
its power from the outside device. When data is being transmitted by the outside device to the
M100AH this LED will flicker.
When you are attempting to configure the RS-232 port, if either of the LED's go out when the
cable is connected, that generally means that there is a grounding problem. Check the relative
ground levels of pin 5 on the DB-9.
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