Rockwell-automation 1771-SPI,D17716.5.122 SPI PROTOCOL INTERFACE Manual de usuario descargar pdf (Pagina 13)

Overview of an SPI Communication Network

Chapter 1

1-7

The SPI specification and previous revisions of the SPI module user

manual use terms that may be unfamiliar to you. We attempt to translate

SPI terms to ones more commonly used on the shop floor so you can more

easily understand concepts of SPI module operation.

SPI Terminology

SPI Term How it works or what it means Shopfloor Term

ASCII Polls ASCII strings such as SPI Revision returned by BTR ASCII status word (32bit word or 2 PLC words)

ASCII Selects ASCII strings that you send to the SPI module ASCII string (32bit word or 2 PLC5 words)

Bit Polls bitlevel status words returned by BTR bitstatus words (16bit words)

Bit Selects bitlevel command words that you send to the SPI module bitcommand words (16bit words)

Device ID SPIspecified code for an SPIspecified device 8bit code such as 00100010 (22) for a dryer

Device Type SPIspecified device mold temperature controller, dryer, hot runner, etc.

Numeric Polls process actuals such as pressure or flow returned by BTR numeric status words (32bit word or 2 PLC5 words)

Numeric Selects setpoints or alarm limits that you send to the SPI module numeric setpoints (32bit word or 2 PLC5 words)

Polls (noun) status returned to the processor by BTR Numeric status, or words containing status bits

Selects (noun) commands transferred to the SPI module by BTW setpoints, or words containing control bits

Station Address address that you select for a device on the SPI network device address

Version latest update revision level

Zone applies to temperaturecontrol devices such as hot runner:

independently controlled area, slave to master controller

such as the barrel, nozzle, or runner, on a molding machine

zone or temperature zone

Zone Addresses slave addresses for a single temperature control device zone address

Other Important Terms

Term Definition

Command bitlevel such as to turn ON a device, or wordlevel such as a setpoint or alarm

Decimal Data the PLC5's base10 (integer) numbering system with a range of -32,768 to +32,767,

stored in N files as 2'scomplement binary in 16bit words

Polling Sequence or

Automatic Polling

The manner in which the SPI module pulls status from each device on the SPI link, formats it,

and sends it to the PLC processor by BTR. The SPI module services the devices (completes

one before going to the next) in the order that you listed them in the MCC polling sequence.

Status bitlevel such as the ON/OFF status of a device, or wordlevel such as a process temperature

Definition of Terms

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Rockwell-automation 1771-SPI,D17716.5.122 SPI PROTOCOL INTERFACE Manual de usuario Pagina 13