Communications; General Rs-232 Troubleshooting; Troubleshooting Calibrator/Modem Or Terminal Operation - Teledyne T700 Operation Manual

Teledyne API – Model T700 Dynamic Dilution Calibrator
9.4.14. RS-232 COMMUNICATIONS

9.4.14.1. General RS-232 Troubleshooting

9.4.14.2. Troubleshooting Calibrator/Modem or Terminal Operation

Note
06873B DCN6388
Teledyne API calibrators 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.
manufacturer observes the signal and timing requirements of the protocol very carefully.
Problems with RS-232 connections usually center around 4 general areas:

Incorrect cabling and connectors. See Section 3.3.1.7 for connector and pin-out
information.

The BAUD rate and protocol are incorrectly configured. See Section 5.2.

If a modem is being used, additional configuration and wiring rules must be
observed. See Section 6.3.

Incorrect setting of the DTE-DCE Switch is set correctly. See Section 5.1.

Verify that the cable (P/N 03596) that connects the serial COMM 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 calibrator.
1. Check cables for proper connection to the modem, terminal or computer.
2. Check to ensure the DTE-DCE is in the correct position as described in Section 5.1.
3. Check to ensure the set up command is correct. See Section 6.2.
4. Verify that the Ready to Send (RTS) signal is at logic high. The T700 sets pin 7
(RTS) to greater than 3 volts to enable modem transmission.
5. Ensure the BAUD rate, word length, and stop bit settings between modem and
calibrator match. See Section 5.2.1.
6. Use the RS-232 test function to send "w" characters to the modem, terminal or
computer. See Section 5.2.3.
7. Get your terminal, modem or computer to transmit data to the calibrator (holding
down the space bar is one way); the green LED should flicker as the instrument is
receiving data.
8. Ensure 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's P/N 013500000.
Troubleshooting and Service
Generally, every
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