(continued)
Description of SPI Communications
The Society of Plastics Industry (SPI) has defined a standard protocol to be used
for interconnecting plastics equipment. This protocol uses the RS-485 standard as
the physical connection and defines stand addresses and commands to communi-
cate with the various kinds of equipment in common use at a typical plastics facili-
ty. For example, a dryer is specified as Device ID 22 hex, a chiller is Device ID 21
hex. The data retrieved for each type of equipment is defined in the standard. For a
dryer or other piece of equipment to be in compliance with the SPI standard you
must be able to retrieve certain parameters such as the setpoint process tempera-
ture, high and low temperature deviation alarms, temperature to the process, tem-
perature to the process, etc. Some parameters are also designated as optional
parameters that may or may not be available depending on the equipment
provider’s discretion.
Installing the SPI Communication
Hardware
The SPI option is available with the DC-2 display boards. The display boards have
a RS-232 port built into the board. The RS-232 to RS-485 converters are provided
and mount on the inside of the door of the electrical cabinet. The RS-485 SPI sig-
nal is then brought to the outside of the cabinet by a 9 pin D-sub connector. Refer
to Conair drawing 130024 and 188629 in Appendix A for details of the installa-
tion. The RS-485 SPI signal is available on pins 4 and 5 of the DB-9 connector.
Pins 8 and 9 also have the RS-485 connection (parallel with pins 4 and 5) to assist
in daisy-chaining equipment together.
Configuring the SPI Communication
Software
The SPI protocol option must be turned on and configured in the operator display
before it may be used.
To setup the SPI communications:
1 Enter the supervisory level password (0210). See your dryer manual for
directions if necessary.
D-2 l SPI Comm un ica tions
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