FYI Document

SPI COMMANDS FOR SENTRA AND MAXIMUM UNITS

Introduction
In 1987 a group of member companies of the Society of the Plastics Industries began development of a communications protocol for use by their processing and auxiliary equipment. Their goal was to allow the exchange of information between various pieces of equipment from different manufacturers to be simple and reliable. The result of their work was released in 1990 and has made the interconnection of equipment much easier and straight forward. There are over 40 companies that offer the SPI protocol in their products.

This document details the implementation of the SPI protocol available in the Sentra mold temperature control and the Maximum portable chiller.

Protocol Basics
The SPI protocol is described by a 2 part specification. The largest portion of the SPI protocol specification deals with how basic information is exchanged between equipment. The second part of the specification details the actual pieces of information exchanged using the protocol. Items such as Process Temperature, Process Setpoint and Process Status are detailed in this part. This document lists the commands that are supported by Advantage Sentra mold temperature controllers and Maximum portable chillers.

Equipment Setup
The setup of equipment to be connected in an SPI protocol network is simple. Each device must have a unique address for its device type and it must use the same data transfer rate as the other pieces of equipment in the network. There are many acceptable ways used to 'setup' the device address and data rate. Advantage equipment provides access to the information via the front panel operators and displays. Other manufacturers may use internal DIP switches or jumpers.

A typical cell may be configured as follows:
• Data Transfer Rate : 9600 bits per second (bps)
• Mold Temperature Controllers (qty 2) : Addresses 1 and 2
• Chiller (qty 1) : Address 1

Network Troubleshooting
Troubleshooting a network is best done by verifying the setup of each piece of equipment and insuring that the network is installed with the correct electrical interconnection. Here are some basic things to do if equipment isn't 'talking' as expected.

1. Verify that each piece of equipment is properly grounded to its power source.

2. Inspect cables inside and outside the electrical cabinet. Repair or replace as necessary. The cable scheme used by most manufacturers allows the communication signals to 'pass through' each piece of equipment. Therefore, when a piece of equipment is disconnected from the middle of the network, all the equipment 'after' will be disconnected as well. Therefore, when a piece of equipment is disconnected from the middle of the network, all the equipment 'after' that one will be disconnected too. If a piece of equipment is being permanently removed, the device cables should be rearranged at the molding machine to reconnect the other equipment.

3. Check the Data Transfer Rate and Address of each piece of equipment. For example, if both Temperature Control Units have the same address, they will both try to 'talk' at the same time and garble each other's data.

4. Verify the network is properly terminated and that it is configured as a 'multi-drop'. This is best achieved by following the molding machine manufacturer's installation instructions and use extension cables provided by them or us.

5. Attach each device, singly, to the molding machine and see if it 'talks'. Add additional devices until a problem is seen.

SPI COMMANDS FOR Sentra 'SK' Temperature Controllers

POLL
C1 C2
20 20
20 20
20 30
20 32
20 34
20 36
20 40

SELECT
C1 C2
20 21

20 31


20 37

COMMAND
Echo
Version
Setpoint
High Temp
Low Temp
Flow Alarm
Status Process

DESCRIPTION
Controller integrity command
Controller version command
Desired process temperature
Hi temperature deviation alarm
Low temperature deviation alarm
Low flow alarm setpoint

POLL
C1 C2
20 42

SELECT
C1 C2

COMMAND
Status Machine 1

DESCRIPTION

POLL
C1 C2
20 44

SELECT
C1 C2

COMMAND
Status Machine 2

DESCRIPTION

POLL
C1 C2
20 48

SELECT
C1 C2
20 49

COMMAND
Machine

DESCRIPTION

POLL
C1 C2
20 4A

SELECT
C1 C2
20 4B

COMMAND
Protected Mode - Machine

DESCRIPTION

SPI COMMANDS FOR Maximum 'MK' Portable Chillers

POLL
C1 C2
20 20
20 20
20 30
20 32
20 34
20 36
20 40

SELECT
C1 C2
20 21

20 31


20 37

COMMAND
Echo
Version
Setpoint
High Temp
Low Temp
Flow Alarm
Status Process

DESCRIPTION
Controller integrity command
Controller version command
Desired process temperature
Hi temperature deviation alarm
Low temperature deviation alarm
Low flow alarm setpoint

POLL
C1 C2
20 42

SELECT
C1 C2

COMMAND
Status Machine 1

DESCRIPTION

POLL
C1 C2
20 44

SELECT
C1 C2

COMMAND
Status Machine 2

DESCRIPTION

POLL
C1 C2
20 48

SELECT
C1 C2
20 49

COMMAND
Machine

DESCRIPTION

POLL
C1 C2
20 70
20 72

SELECT
C1 C2

COMMAND

DESCRIPTION
Temperature to process
Temperature from process
Blanket Poll
20 30 Setpoint
20 32 High alaram deviation
20 34 Low alarm deviation
20 40 Status process
20 70 To process temperature

** Cylinder unloading is 0x400. Standard chiller is 0
*** Valid for cylinder unloading only. 3 head is 0x0x800. 2 head is 0.

For more information on SPI commands for temperature control unit and portable liquid chiller call the Advantage Sales Department at 317-887-0729.