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SBC filling system control

SBC filling system control module

Description

Needed a single board computer module to receive data from four different loadcell at rate 1,500 samples per second. This data is received via one each RS485 ports for each loadcell.

These loadcells are part of a filling system consisting of filling nozzles with two valves. Each nozzle is connected to a coarse and fine filling valve. The filling process for each nozzle will start with a filling weight value and a discrete input from a PLC. The tare weight for the filling vessel will be zeroed out before filling starts.

The data from the loadcell need to be massaged too try to eliminate noise and vibration by a smart filter that learns. Also smart filling software needs to adjust to the in-flight of the product and timing of the valves. What this means is that the time that the nozzle valves (Coarse and fine) need to close is updated after each filing weight is reached. This will help correctly adjust the final filling weight value. All of this is necessary and independent for each of the four nozzles.

The process is to start with the opening the coarse and fine nozzle at the same time. After a preset value the coarse shuts and the remaining fill is done by the fine nozzle until the filling value is reached (–) the time in-flight of the product and time to shut the valve which need to be updated after each fill cycle.

Also needed three manually adjustable filters for frequencies (vibration) from the machine.

All the filters selection and filling data needs to be accessed from the PLC over the serial commutations or Ethernet.

The output data is transmitted to the PLC over the serial module or Ethernet. PLC programming done by others.

Also some discrete outputs are necessary one for each nozzle valve and one to start/stop the pump.

All program source code and documentation is necessary for this project.

Options,

• Small display (6” to 8”) with screens for overview of data input of filters & control and displays of weight value.

System requirements

1. Input single from 4 loadcells by (4) RS485 at a rate of 1,500 samples per second

• Baudrate 115,200 bps

• Data Exchange Listed Below

2. Data massage

a. Do a weighted avg. of data

b. Look for noise or vibration in data and create smart filters to eliminate

c. Create different filters for know frequencies

3. Output to PLC CompactLogix

a. 1769-ASCII Module (1)RS485 or Ethernet port

b. Output weight data at a rate of 50 ms

c. Allow selection of different data filters

4. Hardware

a. Prefer PC/104 but any SBC is fine.

b. Completed in box preferred but open board is fine.

c. Ethernet connection

Data exchange

1.1 EVC Mode

If the module is set in EVC mode using the switches on the module as described later (setting SW1.6 to OFF and repowering the module), the module will communicate with the following specifications:

Specification: RS485 (2-wire)

Baudrate: 115200 bps

Data bits: 7

Parity: Even

Stop bits: 1

Protocol: EVC protocol described below (Transmit Only)

1.1.1 EVC Protocol Format

After each sample period (2 ms) a new weight telegram is transmitted. The transmitted telegram has the following format:

<LF>WWWWWWWW<CR>

Each telegram contains a line feed character, a weight result and a carriage return character. The telegram contains:

<LF> Line Feed character (ASCII 0Ah).

WWWWWWWW Weight value for the loadcell. The value is an 8 byte ASCII hex number with MSB first.

<CR> Carriage Return character (ASCII 0Dh).

1.2 BIN Mode (Binary Mode)

If the module is set in BIN Mode (Binary Mode) using the switches on the module as described later (setting SW1.6 to ON and repowering the module), the module will communicate with the following specifications:

Specification: RS485 (2-wire)

Baudrate: 115200 bps

Data bits: 8

Parity: None

Stop bits: 1

Protocol: BIN protocol as described below (Transmit Only)

1.2.1 BIN Protocol Format

After each sample period (2 ms) a new weight telegram is transmitted. The transmitted telegram has the following format:

<STX>WWW<BCC>

Each telegram contains a start character, a weight result and a checksum. The telegram contains:

<STX> STX character (ASCII 02h).

WWW Weight value for the loadcell. The value is a 3 byte binary hex number with MSB first.

<BCC> Checksum.

The checksum is calculated by logical XOR of all characters in the telegram including the STX character.

Skills: Engineering

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About the Employer:
( 0 reviews ) wrightstown, United States

Project ID: #205748