Allen Bradley Plc Slot Numbering
- Allen Bradley Plc Port Number
- Allen Bradley Plc Slot Numbering Machine
- Allen Bradley Plc Slot Numbering Chart
- Allen Bradley Plc Slot Numbering Software
- Allen Bradley Plc Slot Numbering Tool
The PLC Properties object includes current device information about various possible faults, status, version, time, slot, serial number, and name. The following is an example of a successful read, where an instruction’s Result Key is myProgramDint, and the Destination Path is destination.allenStart. We then need to specify the IP address of the slot number on the second control logix PLC that holds the ENBT module. In this example, that IP address is 192.168.0.56. From there, we need to go to the backplane of the second control logix PLC, which again is a value of one, and then we want to end at the processor in slot zero. 3 - AB Version 14 or earlier: Allen-Bradley PLC version 14 and earlier use the full Connection Path, 01 00 20 02 24 01 2c 01. Retries: This is the number of times that the Panel will Retry to send a message if the request does not receive a reply in the specified Timeout period.
Introduction
There are two distinct ranges of Allen Bradley PLC Devices:
| Model Types | Summary |
|---|---|
| SLC-500, MicroLogix, PLC-5. | These models are configured using ladder logic and store data in files. Tags in Fernhill SCADA are mapped to locations in the data files. The File Data Address Format defines which location in the PLC is mapped to a Fernhill SCADA Tag. Fernhill SCADA uses this tag format when the PLCType Configuration Property is set to 0 (Micrologix, SLC and PLC-5). |
| ControlLogix, CompactLogix. | These models implement the IEC 61131-3 standard and each data item is assigned a unique variable name. Tags in Fernhill SCADA are mapped to variables in the PLC program. The Variable Reference Format defines which variable in the PLC is mapped to a Fernhill SCADA Tag. Fernhill SCADA uses this tag format when the PLCType Configuration Property is set to 1 (ControlLogix or CompactLogix). |
File Data Address Format
This File Data Address Format is used with MicroLogix, SLC and PLC-5 range of PLC Devices.
The File Data Address Format is a string that defines the location of data in a file based Allen Bradley PLC. The format of the string is:
Xf:e.w/b
Where:
- X is the file type.
- f is the optional file number.
- e is the element number.
- w is the optional word offset.
- b is the optional bit offset.
File Type
Data in Allen Bradley PLC Devices is stored in files. For example there are separate files for Inputs, Outputs, Status Bits, Timers, Counter, Integers and so on. Some file types are fixed, for example there can only be one file each for Inputs, Outputs and Status Bits. Other files are more flexible, for example there can be multiple Integer files.
| File | Type | Notes |
|---|---|---|
| O | Outputs | If used, the File Number must be 0. The Element Number sets the I/O slot. The Word Offset sets the word offset within the I/O slot. The Bit Offset sets the bit number (0-15). |
| I | Inputs | If used, the File Number must be 1. The Element Number sets the I/O slot. The Word Offset sets the word offset within the I/O slot. The Bit Offset sets the bit number (0-15). |
| S | Status | If used, the File Number must be 2. The Element Number sets the status word. The Bit Offset sets the bit number (0-15). |
| B | Bit | The File Number sets which bit file to use (3, 9-255). If not used, the File Number is 3. The Element Number sets the word. The Bit Offset sets the bit number (0-15). |
| T | Timer | The File Number sets which timer file to use (4, 9-255). If not used, the File Number is 4. The Element Number sets the timer index. The Word Offset sets the word offset within the timer (0-2). The Bit Offset sets the bit number (0-15). |
| C | Counter | The File Number sets which counter file to use (5, 9-255). If not used, the File Number is 5. The Element Number sets the counter index. The Word Offset sets the word offset within the counter (0-2). The Bit Offset sets the bit number (0-15). |
| R | Control | The File Number sets which control file to use (6, 9-255). If not used, the File Number is 6. The Element Number sets the control index. The Word Offset sets the word offset within the control (0-2). The Bit Offset sets the bit number (0-15). |
| I | Integer | The File Number sets which integer file to use (7, 9-255). If not used, the File Number is 7. The Element Number sets the word. The Bit Offset sets the bit number (0-15). |
| F | Float | The File Number sets which float file to use (8-255). If not used, the File Number is 8. The Element Number sets the float index. |
| ST | String | The File Number sets the which string file to use (9-255). The Element Number sets the string index. The Word Offset sets the word offset within the string (0-41). |
File Number
In an Allen Bradley PLC, data is organized as files. The File Number is optional and, if included, sets which file to access. If the File Number is not included the file number is implied by the File Type. All PLC Devices have a predefined set of files as follows:
| File | Type |
|---|---|
| 0 | Outputs |
| 1 | Inputs |
| 2 | Status |
| 3 | Bit |
| 4 | Timer |
| 5 | Counter |
| 6 | Control |
| 7 | Integer |
Notes:
Allen Bradley Plc Port Number
- On a MicroLogix 1000 PLC no additional files can be defined.
- On a MicroLogix 1200 PLC, SLC 5/01 CPU, or SLC 5/02 CPU file 8 is reserved. Additional file numbers 9 to 255 are user defined.
- On a other PLC types file 8 is a Float file. Additional file numbers 9 to 255 are user defined.
Element Number
The Element Number sets which element of the file to access.
For Input and Output files, the Element Number indicates which I/O slot to access. An I/O slot may consist of 1 word, or multiple words depending on the type of I/O configured.
For other file types, the Element Number sets which element to access.
Word Offset
The Word Offset field is optional, and if used, defines which word of a multi-word element to access.
Bit Offset
The Bit Offset field is optional, and if used, defines which bit of the word to access.
Data Address Editor
The Data Address Editor provides a convenient tool to build Allen Bradley File Data Address strings.
To open the File Data Address Editor, click on the Browse button at the right side of the DataAddress field:
Variable Reference Format
The Variable Reference Format is used with CompactLogix and ControlLogix PLC Devices.
The Variable Reference Format is a string that defines the location of variable in a tag based Allen Bradley PLC. The format of the string is:
Variable[VarArrayIndexes].StructMember[ArrayIndex]
Where:
- Variable is the name of the variable in the PLC.
- VarArrayIndexes is an optional set of variable array indexes.
- StructMember an optional structure member name.
- ArrayIndex is an optional array index on the structure member.
Examples
Some examples of Allen Bradley File Data Addresses:
| Address | Description |
|---|---|
| O:1, O0:1, O:1.0 | The first word of output slot 1. |
| O:1/0, O0:1/0, O:1.0/0 | The first bit of the first word of output slot 1. |
| I:5.1, I1:5.1 | The second word of input slot 5 |
| N:20, N7:20 | Word 20 of the default integer file |
| N:20/15, N7:20/15 | Bit 15 of word 20 of the default integer file |
| N10:15 | Word 15 of user defined integer file 10 |
Some examples of Allen Bradley Variable References:
| Address | Description |
|---|---|
| FlowTemperature | A reference to a variable called FlowTemperature. |
| SCADAData.Pressure | A reference to Pressure member of the variable SCADAData. |
Where Used
The Allen Bradley PLC Data Address Format is used in these contexts:
- In the IOItemName field of an I/O Analog Data Point Tag when the tag is associated with an Allen Bradley PLC.
- In the IOItemName field of a I/O Digital Data Point Tag when the tag is associated with an Allen Bradley PLC.
- In the IOItemName field of a I/O Double Word Data Point Tag when the tag is associated with an Allen Bradley PLC.
- In the IOItemName field of a I/O String Data Point Tag when the tag is associated with an Allen Bradley PLC.
- In the IOItemName field of a I/O Word Data Point Tag when the tag is associated with an Allen Bradley PLC.
- In the DataAddress field of an Allen Bradley Register Block.
- In the DataAddress parameter of the DirectWriteBit Tag Command when used with an Allen Bradley PLC.
- In the DataAddress parameter of the DirectWriteWord Tag Command when used with an Allen Bradley PLC.
Further Information
To learn about Allen Bradley Register Block Tags.
For an overview of the Allen Bradley Driver.
Allen Bradley Plc Slot Numbering Machine
For the meaning of terms used in Fernhill SCADA.
Fernhill SCADA Version 3.63. Copyright © 2012-2020 Fernhill Software Ltd: All rights reserved.
Introduction
Understanding the Hardware is the first step of working with Programmable Logic Controllers (PLCs). In this tutorial, we will be going over the entire ControlLogix platform which is the flagship product from Rockwell Automation.
ControlLogix is classified as a large control system which is typically used in plant-wide applications. This platform allows PLC Programmers to have full control over various local and remote systems. ControlLogix hardware is critical in many facilities and provides a level of flexibility, unlike any other PLCs. Furthermore, it has the most memory and fastest speed available when compared to other systems from Allen Bradley.
In this article, we will talk about the basics you need to know: Chassis, Power Supply & 1756 Control Logix Family.
ControlLogix Chassis Hardware Components
ControlLogix is characterized by the 1756 prefix. You will find this number in front of every component which works with this system. This includes PLCs, I/O Modules, Chassis, Communication Modules and more. This is important to know as Rockwell has secondary identifiers for their devices which often confuses new Automation Engineers. The part number is different from the revision number; the part number for ControlLogix will always include “1756” as the prefix.
ControlLogix Chassis Selection
The Chassis is what will physically hold the modules which allow the system to interface field devices: EtherNet, ControlNet, DeviceNet, Analog Inputs, Digital Outputs, etc. The chassis can be selected based on the constraints of the system as well as the mechanical layout of the panel. However, based on my experience, it’s always best to purchase the largest chassis possible in order to leave room for future expansion. The cost difference in the different models is fairly low, so going with the 17 slot chassis is always the best option in my opinion.
The chassis for 1756 ControlLogix modules can be of following sizes:
- 4 slot (1756-A4)
- 7 slot (1756-A7)
- 10 slot (1756-A10)
- 13 slot (1756-A13)
- 17 slot (1756-A17)
ControlLogix Power Supply Selection
A power supply will provide power to the chassis as well as the modules connected to it. ControlLogix power supplies will snap into place on the left side of the chassis and become an integral part of the PLC rack.
Here’s a breakdown of standard power supplies which should be your number one option in most cases. Do note that you need to select what’s best for your system depending on where it’s going to be used. In my experience, going with the 24VDC option is always the safe bet as factories can always provide this voltage level regardless of their location and thus you don’t need to be concerned with input voltage levels.
If you’re going to deploy a control system within an environment with extreme temperatures, it would be wise to invest in a properly rated power supply. Here are your best options for such environments:
Allen Bradley Plc Slot Numbering Chart
Lastly, if the system which will be attached to this chassis requires redundancy, the following selection would be best. These systems require an uptime which is highly critical and could result in damage to the equipment or personnel in case of failure. Investing in a redundant power supply would be recommended.
ControlLogix Hardware Important Terms
Allen Bradley Plc Slot Numbering Software
Chassis Backplane
As mentioned above, the chassis will provide a connection between all the modules inserted into it. The primary goal is to send data between the PLC and other cards such as I/O, Communication modules and Specialty Modules.
The backplane, in particular, refers to the portion of the chassis which send the signals between the modules. This term is often used within RSLogix 5000 & Studio 5000 documentation as well as the software. It’s important to understand that this term will be referenced in order to identify which modules are positioned in the chassis.
Chassis Slot
As we discussed above, the chassis for the 1756 ControlLogix family will have 4, 7, 10, 13 or 17 slots. This number refers to the available spaces within the chassis. A single slot will be able to accommodate a single 1756 card. The slot numbers on the chassis will be labeled starting from 0. The same numbers will be used within the RSLogix & Studio 5000 environments as you configure which cards are positioned in which slot.
There’s no right or wrong way to position your modules within the chassis, but I would try to be consistent and group similar modules. My preferred method has been as follows:
- PLC cards
- Comm cards (EtherNet, DeviceNet, ControlNet, Sercos)
- DC Inputs
- DC Outputs
- Analog Inputs
- Analog Outputs
- AC Inputs
- AC Outputs
- Relay Outputs
- Specialty Modules
Conclusion
Allen Bradley Plc Slot Numbering Tool
The ControlLogix family offers an excellent control system for a large application. It’s highly scalable and supports a wide variety of modules for all purposes. Some examples include high-performance PLCs, Inputs, Outputs, Analog I/O, Relay Cards, Specialty Cards (RTD, HART, High-Speed Counter, etc.), Communication (EtherNet, DeviceNet, etc.)
Understanding the hardware is important as an engineer, PLC programmer and technician. Remember that a chassis is what’s used to host your cards, the backplane is the medium over which the cards communicate and the slot refers to their position within the chassis. These terms are frequently used within the documentation as well as program configuration through RSLogix & Studio 5000.