Teledyne API Model 200AH NO
X
Analyzer Instruction Manual, 06492, Rev. G2
9-36
9.3.2.1. RS-232 Port
If the RS-232 port is not working, check the following:
Physical Wiring
Refer to Figure 9-3 for the wiring diagram of the DB-9 plug on the M200A rear panel. There are
two features that make connecting the wiring easier. First is the red/green LED’s on the rear
panel. One device (such as the M200AH) provides the power to run the red LED, the other
device will provide the power for the green LED. If the wiring is hooked up correctly both
LED’s will be illuminated. There is a DTE-DCE switch, this switch interchanges pin 2 & 3 on
the
DB-9 connector. Set the DTE-DCE switch so that both LED’s are illuminated.
RS-232 Protocol (BAUD rate, Data bits, Parity)
The communication protocol for each instrument must match. In Figure 9-3 the default RS-232
parameters are listed. The BAUD rate can be changed in the software menus under SETUP-
MORE-COMM-BAUD.
Data Communications Software for a PC
You will need to purchase a software package so your computer can transmit and receive on its
serial port. There are many such programs, we use PROCOMM at Teledyne API. Once you set
up the variables in PROCOMM and your wiring connections are correct, you will be able to
communicate with the analyzer.
If connecting to a modem, check the following:
Modems are especially difficult because they may have pins that need to be at certain EIA RS-
232 levels before the modem will transmit data. The most common requirement is the Ready to
Send (RTS) signal must be at logic high (+5 V to +15 V) before the modem will transmit. The
Teledyne API analyzer sets pin 8 (RTS) to 10 volts to enable modem transmission.
To troubleshoot a modem connection first disconnect the RS-232 cable from the Analyzer and
verify (use a DVM) that you are getting a signal on Pin 2 of the RS232 port on the Analyzer. The
signal will be between -5V and -15V with respect to signal ground (pin 5). If not, there is a
problem with the CPU board or the cable. This is the transmit (TD) signal out of the Analyzer.
This should then be connected to TD input on the modem, normally Pin 2. You may need to
change the DTE/DCE switch on the M200AH so the signal is on Pin 2 of the modem.
Go to the cable connected to the modem/terminal and verify (use a DVM) that you are getting a -
5 V to -15 V signal on Pin 3 of the cable. This pin should be connected to Pin 3 of the Teledyne
API Analyzer.
