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Teledyne API – Model T700 Dynamic Dilution Calibrator Troubleshooting and Service
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9.4.14. RS-232 COMMUNICATIONS
9.4.14.1. General RS-232 Troubleshooting
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. Generally, every
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 u
sed, additional configuration and wiring rules must be
observed. See Section 6.3.
Inc
orrect setting of the DTE-DCE Switch is set correctly. See Section 5.1.
Verify that th
e cable (P/N 03596) that connects the serial COMM ports of the CPU
to J12 of the motherboard is properly seated.
9.4.14.2. Troubleshooting Calibrator/Modem or Terminal Operation
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.
Che
ck to ensure the set up command is correct. See Section 6.2.
4. Verify that th
e 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-2
32 test function to send “w” characters to the modem, terminal or
computer. See Section 5.2.3.
7. Get your term
inal, 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.
Note Further help with serial communications is available in a separate manual
“RS-232 Programming Notes” Teledyne API’s P/N 013500000.
06873B DCN6388