TENNEY ENVIRONMENTAL
Tenney Junior Test Chambers: Models TJR and TUJR, W942, or WF4
Page 17
DATA COMMUNICATIONS - WATLOW 942
As an option, your chamber may include data communications with the main controller's serial port. When
employed, a Data Communications manual will be included in the Supplemental Instructions Section. As a
reference, the available data types are listed and briefly described below.
RS232C / RS423A: Both interfaces are compatible and use 3 wires: a single transmit wire; a single receive
wire; and a common line. The maximum wire length is 50 feet. Only a single chamber may be connected to
your computer. Data signals are measured as plus and minus 12 Volts to common with RS232C, and plus
and minus 5 Volts to common with RS423A.
RS422A: This interface uses 5 wires: a transmit pair; a receive pair; and a common line. Up to ten
chambers may be connected to your computer on a multi-drop network up to 4,000 feet long. Data signals in
each pair are measured as a plus or minus 5 Volt differential.
EIA-485: This interface uses only 2 wires. Both wires are used for transmitting and receiving data, and
therefore, only one device may talk at a time. Up to 10 chambers may be connected to your computer on a
multi-drop network up to 4,000 feet long. Data signals are measured as a plus or minus 5 Volt differential. An
EIA-485 card must be installed for signal conversion.
IEEE-488: This is a parallel multi-drop interface with several control and data lines. Each device connected
must be set to a unique address. Data from other test devices may also be collected. An IEEE-488 to serial
converter card must be installed. Maximum cable length is approx. 33 ft.
DATA COMMUNICATIONS - WATLOW F4
Data communications utilizes EIA-232 and EIA-485 serial interface with Modbus RTU protocol. Modbus RTU
enables a computer or PLC to read and write directly to registers containing the controller's parameters.
These data interface types are briefly described below.
Controller Configuration:
The pre-programmed controller configuration for your chamber is documented in the Test Report, which is
located in the Supplemental Instructions Section. Refer to the controller’s user manual for more information.
Important! The configuration set-up is mainly provided for your reference. Not all of the parameters shown
apply to your chamber. Changes to some of the set-up parameters may drastically affect your chamber
performance and void your warranty. Contact the Lunaire Service Dept. before attempting any changes.
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