RMC Register Map (Allen-Bradley)

Tip: RMCWin's Address Tool provides an easy way to identify addresses in the RMC. Simply open the Address Tool and then move the cursor to any field in RMCWin that represents an RMC Register, and the Address Tool will display the address in the address format of your choice. See Address Tool for details.

The RMC module has 64K (65536) 16-bit registers that can be read from or written to over Ethernet, Serial, Modbus Plus, and PROFIBUS-DP. Each register is assigned an address. However, under the different communication methods, different addressing schemes are used. This topic describes using Allen-Bradley PLC addressing. For details on addressing from other modules refer to the following topics:

• RMC Register Map (Automationdirect.com)

• RMC Register Map (Modbus/TCP and Modbus/RTU)

• RMC Register Map (Omron FINS)

• RMC Register Map (Siemens TI505)

• RMC Register Map (Siemens S7)

• RMC Register Map (Modbus Plus)

• RMC Register Map (PROFIBUS-DP Message Mode)

Allen-Bradley offers several Ethernet and serial solutions for its ControlLogix, SLC, PLC-5, and SoftLogix 5 controllers. In addition, SoftPLC emulates the PLC-5 and therefore also uses Allen-Bradley's Ethernet protocol. Over this protocol, the RMC's registers are broken into a number of integer files. Each integer file used (N7, N9-N18, L19, N20-N255) is configured to be the maximum size allowed on a SLC 5/05 file: 256 elements: Nf:0-255. For details on reading and writing these registers, see the following topics:

• Using Allen-Bradley Controllers with the RMC ENET

• Using SoftPLC's SoftPLC with the RMC ENET

• Using DF1 (Full- and Half-Duplex) with the RMC SERIAL

Status Registers:

These registers can only be read; writes are ignored.

Command Registers:

These registers can be read or written.

Parameter Registers:

These registers can be read or written. Changes to these registers do not take effect until a Set Parameters (P) command is executed.

Event Step Table Registers:

These registers can be read or written. When using the Allen-Bradley addressing scheme with these registers, you must keep in mind that the Event Step Table is split over eight register files (this is done because the SLC 5/05 only supports 256 words per file). Use the following table to determine the register file for a given event step:

Note: On Allen-Bradley PLCs, reads and writes that extend beyond the end of an RMC register file will continue into the next file or files. This is particularly useful on the ControlLogix, which allows reading large amounts of data with a single MSG block. For example, by reading 2048 integers starting at N9:0 in the RMC, the entire Event Step table can be read into the ControlLogix.

The register map for addressing the fields in the event step table is as follows:

Input to Event Table Registers:

These registers can be read or written.

Status Map Registers:

This block of registers is only used by the Modbus Plus and PROFIBUS interfaces. Therefore, these registers are unused by this Ethernet protocol.

Plot Type Registers:

The plot type registers can be read or written. The values that are read indicate the extra plot information in the current graph. The values written to these registers tell the controller which extra plot information to obtain on the next plot. For these registers, the following values are used:

• 0: Extra position precision

• 1: Command and Command Value

• 2: Event Step and Link Value

• 3: Raw Transducer Counts

• 4: Internal Target and Actual Speeds

• 5: Integral Drive

For more information on these four types of plot information, see Selecting the Data to Plot and Reading Plots from the Communication Module.

Digital (Discrete) I/O Registers:

These registers indicate the current state of the digital inputs and outputs. These registers may only be read; writes will be ignored, as this product does not support forcing inputs or outputs.

Because different PLCs label bit numbers differently, the following chart is provided to show the mapping between the devices:

The bit numbers listed in the table below are in RMC format (0 is LSB, 15 is MSB):

Plot Time Registers:

The Plot Time interval is configurable on the RMC. This interval indicates the number of control loops between each sample in a plot. Therefore, if the control loop is 0.976ms (e.g. RMC100-M1), this value indicates roughly the number of milliseconds between samples. If the control loop is 1.953ms (e.g. RMC100-M4), this indicates half of the number of milliseconds between samples.

These registers may be read or written. When read, they indicate the plot interval of the currently gathered plot. When written, they set the plot interval the RMC should use for the next plot it will gather. When the RMC starts the next plot, it copies the requested plot interval into the currently used plot interval.

Last Parameter Error Registers:

Note: To use these registers through Ethernet, you must have RMC100 CPU control firmware dated 19990715 or later and Ethernet firmware dated 19990702 or later.

Each of these read-only registers holds the number of the last parameter error generated on an axis. This is useful for determining the cause of the Parameter Error bit in the status word. For a description of the values read from these registers, see Parameter Error Values.

Firmware Date Registers:

Note: To use these registers through Ethernet, you must have RMC100 CPU control firmware dated 19990715 or later and Ethernet firmware dated 19990702 or later.

These read-only registers hold information about the firmware versions in the RMC100 CPU module. The Boot and Loader firmware versions have no effect on the actual performance of the RMC and therefore can usually be ignored.

Transducer Counts (32-bit) Registers:

Note: To use these registers through Ethernet, you must have RMC Ethernet firmware dated 20020115 or later.

Each of these read-only registers holds the transducer counts for an axis. Notice that these registers are 32-bit registers. The low 16 bits will match the Counts register read from registers N7:3, N7:13, etc. However, when the transducer counts go below zero (for incremental transducers) or above 65,535 counts, some information is lost. By using these registers, all bits of the counts are available.

Reserved Registers:

Reading these values will return zero, and writes are ignored.

Spline Download Area:

These registers are write only. Reading them will return zero. This area is used to download intervals and points in a spline. This is a much more efficient alternative to using individual New Spline Point and Set Spline Interval/End Segment commands. For details on using this Spline Download Area, see Downloading Splines to the RMC.

Plot Registers:

These registers can only be read; writes are ignored.

Note: Reading plots is not a trivial task; for further details, see Reading Plots from the Communication Module.

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