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Did You Know? - Various Control Options

by Glenn Johnson

Applied Motion Products has a long history of making products that are simultaneously powerful and easy to use. While this remains a priority for us, the sheer number of variables can seem a bit daunting to a newcomer. Let’s take a step back and examine the different options.

While all of our current generation drives offer advanced current control and anti-resonance algorithms, in terms of usability they can be loosely grouped into the five most popular categories of programmability, or “intelligence”.

The shiny new “R” step drive (link) offers advanced current control and anti-resonance algorithms, allowing very smooth control of a standard 2-phase stepper motor. It was designed for extreme ease of use, being entirely configurable with DIP switches. No computer is required to commission the drive, and it will respond to industry-standard pulse/direction signals for motion.

The “R” drive is mentioned here for completeness. Not technically a programmable drive at all, it is also the only option we offer that is exclusively available for step drives. All the other options below are available on step and servo drives alike.

The ubiquitous “S drive” is a drive with a “-S” in the middle of the model number. Some examples include the ST5-S, STAC5-S-N120, and SVAC3-S-E120. These drives offer all the same motor control options as their more advanced brothers such as advanced current control and anti-resonance algorithms, and are very easily commissioned with our free configuration software. These drives will accept SCL commands sent over a serial or Ethernet link (depending on drive type), step/direction signals, analog inputs for velocity, position or torque, and all have a range of outputs that can be configured to perform specific functions like controlling a motor brake, notifying the PLC of an alarm condition, etc. The difference is that the “S drive” will not accept a stored program. In layman’s terms, it won’t do anything until you tell it to. Note that these drives are available with RS-232, RS-485 and Ethernet communication options.

The venerable “Q drive” builds on the foundation laid by the “S drive” above. It will do everything an “S drive” will do, with the additional capability of storing and executing a Q program. Some examples include ST5-Q-NN, STAC5-Q-N120, and SVAC3-Q-E120. A Q program can be a simple indexing routine or a very complicated positioning sequence with many different operations all tightly coordinated. While very powerful, the Q language is a simple one to learn. Composed entirely of SCL commands, Q programs can be written quickly and effectively by most users with at least some programming experience. Note that these drives are available with RS-232, RS-485 and Ethernet communication options.

The all-powerful “Si drive” builds on this foundation again by adding support for an additional programming environment: Si programming. Some examples include ST5-Si-NN, STAC6-Si, and BLuAC5-Si. “Si” stands for “Simple Indexer”, and is just that. It is best used when a relatively simple sequence of moves must be automated. It is intended for use by individuals with little to no programming experience (though even master programmers appreciate the ease of use and rapid programming capabilities). Note that these drives are available with RS-232 or RS-485 communication options only. Further, note that the Si option is not available for every drive type; look closely at the model listings on the website or contact Applied Motion Products for details.

The next category, the “IP drive” (link), is at its core, a Q drive. It is given a different part number with the letters “IP” in place of the more common “S”, “Q” or “Si”, but it can be thought of as a Q drive that is specifically intended for use on EtherNet/IP-based control networks. There is a common misconception that “Ethernet”, the same networking scheme you’re using to get on the internet and read this newsletter, is the same as “EtherNet/IP”. They are indeed related, but don’t let the names fool you. The explanation can get a bit complicated, so if you’re squeamish you might want to close your eyes until you’re done reading this next section.

Our “Standard Ethernet” drives use the standard Ethernet hardware (CAT5 cable, routers, etc) and UDP and TCP protocols to send our SCL commands between the host and drive. “EtherNet/IP” uses the same Ethernet hardware but is actually a very powerful industrial communication protocol defined by an international standards body to make sure devices from different vendors can communicate. That is, it uses the same wires to send the data, but the data that is sent is different. Think of it like this: Let’s say someone speaks to you in a language you don’t understand. You can hear the words just fine (same physical layer: in this case, sound), but you can’t communicate verbally (different protocols / languages).

Okay, you can open your eyes now.

In summary, EtherNet/IP is widely used all over the world in industrial machinery, and is a must-have for communication with Allen-Bradley control systems. If you just want a drive with an Ethernet jack on it, go with a standard -S or -Q drive, and choose the Ethernet option.

Speaking of international standards, many of our drives are available with CANopen. Some examples include ST5-C-CN, STM23C-3CN. This is yet another industrial communication option, administered by an international standards body for the purpose of sending data to and from the drive. Unlike EtherNet/IP, CANopen defines a physical layer as well, so you’ll notice that these drives have a different plug and require specific wiring. These drives are a great fit for applications where a CANopen network already exists.

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