Despatch 926E Equipment Manual (C-155)Rev 2/11 - Manual (Page 50)

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IEEE 488 Interface Converter
The interface converter has the ability to output signal levels that are compatible with
either RS-232 or RS-422. An internal DIP shorting plug determines which electrical
specification is chosen. If the interface is to be connected to an IBM PC/XT/AT/PS2 or
compatible, the RS-232 level should be selected. If it will be connected to a Macintosh
512K/Plus/SE/II, the RS-422 level should be used. For connection to other computers,
refer to the manufacturer's manual to determine which levels are supported. Most
Watlow controls are available both in RS-232 and RS-422 hardware. Make sure to
match your Watlow device. RS-232 is most common.
RS-232/RS-422 Signal Level Selection
The interface converter's factory default signal levels are compatible with RS-232. To
select RS-422 levels, carefully remove the 8-position shorting plug with a small flat
blade screwdriver from J106. Install the DIP jumper into J205, making certain that all of
the pins on the shorting plug are inserted correctly. The RS-232 position generally
works best with the Watlow controls.