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CAM500 Memory Module

The Niobrara CAM500 is a SY/MAX® register rack compatible memory module. The CAM500 features 520,192 nonvolatile registers which can be stored, retrieved or deleted through the register backplane and/or through a SY/MAX® compatible port on the front of the module. The CAM500 performs data storage, searching, and retrieval with minimum ladder programming. The module performs arbitration between multiple external accessors. By relieving the ladder programmer of these complex problems, the CAM500 greatly simplifies building robust applications involving data storage and retrieval.

Store and Retrieve:

  • Pick lists
  • Routing tables
  • Recipes
  • Tables of correspondence
Data Logging:
  • Alarms
  • Events
  • Statistics
  • Reports

Registers are grouped together into records. The number of registers in a group is user defined and called the record length. The CAM500 is designed for storing and retrieving data by record number and/or by key. The key is a user-defined identifier stored as the first part of the record that must be unique for each record. Records are grouped together inside the CAM500 into files and files are accessed through register rack windows. Multiple windows can exist for each file and multiple files can exist on the CAM500 for storing and retrieving records of different lengths and/or key structures in the same module.

The total number of records the CAM500 can store is determined by the number of files and the number and length of the records. The rack space required for the CAM500 is determined by the number of files, the number of windows for each file, and the length of the records.

The CAM500 storage area is flexible! Records can be accessed by record number or key, record lengths are user defined, records are grouped into files, multiple files can exist in the CAM500, multiple windows can exist for each file, and multiple processes or areas of ladder code can access the same data simultaneously.

The CAM500 is rack addressed like other register rack modules. The minimum register rack address space is 9 registers plus the user defined record length per file. The maximum available register rack address space in the CAM500 is 2,048 registers. The baud rate of the front port is set in a rack register from the processor or using the CAM500SW configuration software that is supplied with the unit. A file is set up in the register rack address space and consists of a record length register, the number of windows register, the number of records register, the length of the key register, a command register, a status register, the record number register and the registers where the record appears. See the CAM500 Rack Image Description below for the order of the registers and the valid values each register can have.

Multiple file windows can be opened into the CAM500 allowing an operator interface, computer, another PLC or other input device to update data through one file window while the ladder program accesses records using another file window. The ladder program can also have more than one file window open into a file in the CAM500. The average time required to retrieve a record in the CAM500 is 0.4 milliseconds when the record has a 3 register key and a record length of 8 registers, and the CAM500 is storing 30,000 of these type records. The CAM500 uses a hashed search and retrieval time is optimized if less than 75% of the available records are in use.


Dimensions: Standard SY/MAX register module. 1.5" wide by 13" tall by 6.5" deep. Approximately four pounds net. Rugged welded steel enclosure with baked on finish. All connectors and indicators are front mounted except the SY/MAX bus card edge connector on the back.

Power Requirements: From SY/MAX bus. 5 volts, 1.1 A.

Port 0: SY/MAX compatible RS-422 with same pinout as SY/MAX processor. DB9 female connector with slide lock posts. 300 to 9600 baud; even parity.

Indicators: Green LED for "Searching"; red LED for "Not Found"

Setup Registers: Processor equivalent registers store the configuration of the unit. These registers are maintained by AC power when present, by power supply when mounted in rack, and by internal capacitor for up to one week when removed from rack.


The CAM500 is available as:

CAM500 with 1 RS-422 port

Effective 11 February 1993 - Specifications subject to change without notice.