K
Hi guys,
Okay, this might not make it through the moderator, but I wanted to say a couple of things about the ControlLogix after the gripefest of the
past few days. <MODERATOR'S NOTE: No problem with vendors responding to product complaints.--Jennifer Powell>
First: Keep it coming. A-B needs as much customer feedback from the guys who use the Logix system as we can possibly get. It's user opinion that makes features and fixes happen. I have thick skin and I'm not a product manager so I like to hear whatever you have to say.
Second: The Logix system is in its infancy; A-B has only been selling the controllers for about a year. A lot of functions and features that were
present in the PLC5 and SLC aren't in the Logix yet. And functions are being added at regular intervals; that's why the seemingly constant
firmware upgrades. Fortunately, the firmware is FLASH and it's an easy utility; I use my Ethernet module to get to the backplane and it usually takes about 10 minutes to upgrade a system. And the firmware support is included in the RSLogix 5000 support contract. If you want to debate whether warranty support of firmware and software should be eternal and free, forget it. That pays my salary; this isn't a hobby for me.
It is a BIG issue that new editions of RSLogix 5000 can't program older firmware controllers, like you can with PLC and SLC. Because of the
compiled nature of the Logix control programs, it's not practical to roll the old compiler into the new build of RSLogix 5000. In the near term,
the solution will be to support the installation of multiple copies of RSLogix 5000 on a single PC with a single activation. You'll still need to
be on your toes and keep track of which versions are operating in your facilities and equipment.
Third: It's not a plot. I spend all day every day getting people familiar with ControlLogix and Rockwell networking. It's new, it's different, and if I'm doing my job right, the newness won't come bite my customers in the butt.
The fact is, I think the Logix is a great controller. Definitely different from the Five, definitely more powerful than the SLC. I've gotten to really like the transportability of code using tag aliasing, and the CIP protocol and object model is like a super-big tub of colorful Legos to me.
At the risk of ticking off Ron Gage, I'd like to take a shot at answering his rhetorical questions:
RhQ:>>Try explaining to a customer why there is no direct communications route from a PLC-5 to a CLogix.
A: Only early Ethernet versions. DH+, DF1, and ControlNet have been compatible since day one, and the PLC5E and ENET sidecar now support CIP
protocol on Ethernet. The Logix needs to emulate the PLC5 addresses, though, so that's an extra step.
RhQ:>>Try explaining to a customer why downloading a program to a CLogix crashes his VAX.
A: I don't know this one. I don't have any VAXes on my networks so I'm not qualified to guess.
RhQ:>>Try explaining to a customer why the DHRIO module is locking up if you use both channels.
A: I think I know this one; did you configure the DHRIO in the I/O Configuration as a RIO scanner and then change that channel to DH+?
That'll disable the DH+ channel if you don't remove the entry from the I/O list and there's no clear error message to indicate that condition.
RhQ:>>Try explaining to a customer how a program that takes 250k on a Pyramid takes over 2 meg on a CLogix.
A: The 5 and 5/250 use a code interpreter, so the code you write is tight and simple and the method for executing it is stored in the ROM of the PLC.
ControlLogix code is compiled, so it's execution method is included in the program file itself. That's an oversimplification, but the difference
between interpreted and compiled code plus the fact that the Logix stores the actual tagnames of your program variables in the controller are what
make the difference. It's not easy to compare PLC program files to Logix (and less easy still when you're talking 5/250 or PLC3) but I use the
equivalency that the base Logix is equivalent to a 5/20, the L1M1 is a 5/40, and the L1M2 is bigger than a 5/80. And I love it that I can walk up to a Logix without having the offline documentation and still have a fighting chance at figuring out the logic because the tagnames are stored in the controller.
RhQ:>>Try explaining to a customer why he can no longer directly enter the ASCII serial number into the PLC (CLogix).
A: You're right on; not only did the Logix not have ASCII instructions, but it didn't even have an ASCII radix display. Both have been added in
version RSLogix 5000 v2.50, but there still aren't string manipulation instructions. I've taken to using DeviceNet to ASCII gateways for most ASCII applications anyhow (instead of using BASIC modules or tying up the serial port) and that's required that I memorize the ASCII table again.
In closing (whew!), if you're using Logix, make sure you're on good terms with your local distributor and keep all your old CDs when you get new software. The "MySupport" notification feature at RSI is a good way to keep up with the release times of the new revisions of Logix.
Cheers,
Ken Roach
A-B Seattle
Okay, this might not make it through the moderator, but I wanted to say a couple of things about the ControlLogix after the gripefest of the
past few days. <MODERATOR'S NOTE: No problem with vendors responding to product complaints.--Jennifer Powell>
First: Keep it coming. A-B needs as much customer feedback from the guys who use the Logix system as we can possibly get. It's user opinion that makes features and fixes happen. I have thick skin and I'm not a product manager so I like to hear whatever you have to say.
Second: The Logix system is in its infancy; A-B has only been selling the controllers for about a year. A lot of functions and features that were
present in the PLC5 and SLC aren't in the Logix yet. And functions are being added at regular intervals; that's why the seemingly constant
firmware upgrades. Fortunately, the firmware is FLASH and it's an easy utility; I use my Ethernet module to get to the backplane and it usually takes about 10 minutes to upgrade a system. And the firmware support is included in the RSLogix 5000 support contract. If you want to debate whether warranty support of firmware and software should be eternal and free, forget it. That pays my salary; this isn't a hobby for me.
It is a BIG issue that new editions of RSLogix 5000 can't program older firmware controllers, like you can with PLC and SLC. Because of the
compiled nature of the Logix control programs, it's not practical to roll the old compiler into the new build of RSLogix 5000. In the near term,
the solution will be to support the installation of multiple copies of RSLogix 5000 on a single PC with a single activation. You'll still need to
be on your toes and keep track of which versions are operating in your facilities and equipment.
Third: It's not a plot. I spend all day every day getting people familiar with ControlLogix and Rockwell networking. It's new, it's different, and if I'm doing my job right, the newness won't come bite my customers in the butt.
The fact is, I think the Logix is a great controller. Definitely different from the Five, definitely more powerful than the SLC. I've gotten to really like the transportability of code using tag aliasing, and the CIP protocol and object model is like a super-big tub of colorful Legos to me.
At the risk of ticking off Ron Gage, I'd like to take a shot at answering his rhetorical questions:
RhQ:>>Try explaining to a customer why there is no direct communications route from a PLC-5 to a CLogix.
A: Only early Ethernet versions. DH+, DF1, and ControlNet have been compatible since day one, and the PLC5E and ENET sidecar now support CIP
protocol on Ethernet. The Logix needs to emulate the PLC5 addresses, though, so that's an extra step.
RhQ:>>Try explaining to a customer why downloading a program to a CLogix crashes his VAX.
A: I don't know this one. I don't have any VAXes on my networks so I'm not qualified to guess.
RhQ:>>Try explaining to a customer why the DHRIO module is locking up if you use both channels.
A: I think I know this one; did you configure the DHRIO in the I/O Configuration as a RIO scanner and then change that channel to DH+?
That'll disable the DH+ channel if you don't remove the entry from the I/O list and there's no clear error message to indicate that condition.
RhQ:>>Try explaining to a customer how a program that takes 250k on a Pyramid takes over 2 meg on a CLogix.
A: The 5 and 5/250 use a code interpreter, so the code you write is tight and simple and the method for executing it is stored in the ROM of the PLC.
ControlLogix code is compiled, so it's execution method is included in the program file itself. That's an oversimplification, but the difference
between interpreted and compiled code plus the fact that the Logix stores the actual tagnames of your program variables in the controller are what
make the difference. It's not easy to compare PLC program files to Logix (and less easy still when you're talking 5/250 or PLC3) but I use the
equivalency that the base Logix is equivalent to a 5/20, the L1M1 is a 5/40, and the L1M2 is bigger than a 5/80. And I love it that I can walk up to a Logix without having the offline documentation and still have a fighting chance at figuring out the logic because the tagnames are stored in the controller.
RhQ:>>Try explaining to a customer why he can no longer directly enter the ASCII serial number into the PLC (CLogix).
A: You're right on; not only did the Logix not have ASCII instructions, but it didn't even have an ASCII radix display. Both have been added in
version RSLogix 5000 v2.50, but there still aren't string manipulation instructions. I've taken to using DeviceNet to ASCII gateways for most ASCII applications anyhow (instead of using BASIC modules or tying up the serial port) and that's required that I memorize the ASCII table again.
In closing (whew!), if you're using Logix, make sure you're on good terms with your local distributor and keep all your old CDs when you get new software. The "MySupport" notification feature at RSI is a good way to keep up with the release times of the new revisions of Logix.
Cheers,
Ken Roach
A-B Seattle