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Application Note
Serial Communications for Isotech Calibration BathsRS232 or RS422?
The majority of Isotech Calibration baths are available with either RS232 or RS422 Serial Communications.
The RS232 option is popular because almost all PC's have an RS232 port as standard. RS422 has the following advantages over RS232,- Several Calibration Baths can be connected to a single serial port
- A Single bath with multiple controllers can be connected to a single serial port
Note that the software protocol is identical for both RS232 and RS422 standards, it is the electrical specifications that differ between the two standards.Isotech recommend RS422 as the preferred serial communications option. A special lead is provided free with RS422 calibration baths to allow connection to a PC's RS232 port. This allows the advantages of RS422 to be realised whilst avoiding the need to either add a special port to the PC or use an external converter. Additional or replacement leads are available Part Number ISO-232-432
A further lead is available as an option, Part Number ISO-422-422 lead which permits up to 5 instruments to be daisy chained together.
Note: The RS 422 standard specifies a maximum lead length of 1200M (4000ft). A true RS422 port will be required to realise such lead lengths. The Isotech conversion leads are suitable for maximum combined lead lengths of 10M which is adequate for most applications.
