Ken Moore

Thanks Ken, The tech note was just what I needed. Ken

Thanks for the 1771 I/O with CLX clarification. I have way more than 16 analog cards per PLC, so I'm going to investigate all my options. How difficult is it to pass data back and forth between PLC-5's and CLX via ethernet or DH+? I currently use ethernet for the HMI and programming, and DH+ to pass data between processors. Since I'm looking to expand versus replace, perhaps adding a CLX system for the expansion would be best. However, it would have to communicate with the 5's, not a lot of data, something like 20-30 words per PLC. Each 5 handles a section of the process, but passes status and permissive words back and forth.

Not having any experience with the CLX line. I always assumed a new CLX processor could be installed and still use the 1771 I/O via RIO adapters. Is this incorrect? I currently have a large production line that is run using three maxed out 5/80E's, with LOTS and LOTS of analog I/O. The 5/80's are maxed out in memory (huge ladder files, lots of block transfers) not on amount of I/O. I had planned on looking into replacing one of the 5/80's with a CLX to get more memory capacity. But it sounds like my plan isn't viable, should I consider adding an additional 5/80 instead?

Tried it again, and worked fine. Don't know what happened the first time. Ken

Down loaded the zip file, nothing there. Did I do something wrong?

You can obtain the software from any Siemens dealer: Siemens software link: Software_Link

Upload the existing program. Open another instance of RSLogix with the new program. Right click on the Ladder file, select copy Goto existing program, click on ladders, new, add new ladder right click on new ladder select paste. add you logic that calls the subroutine. download altered program to PLC. Ken

Does AD have online editing?

Jnelson is correct for most PLC's. Instead of a I/O list, can't they just keep a copy of the program on the laptops? Then when in the field, they open the program, go on line. Comments should be present.

File Name: SLC ADD MANY REGISTERS AND AVERAGE THE VALUE File Submitter: Ken Moore File Submitted: 17 Dec 2004 File Category: PLC Sample Code Example that adds 100 integers using loop logic then gets the average value of the 100 values. Number of integers added can be modified as needed. Click here to download this file

I work in the process chemical industry now, but I've used the bit shift in the past. My explanation may be off a bit, but I'll give it a go. Imagine you a multi step process for filling bottles, a value of 1 indicates a good bottle. A bottle is detected at step 1, a value of 1 is written to a tracking register at bit 0. Then the machine indexes to step 2, we then use BSL to move the 1 from bit 0 to bit 1. At step 2, the value of bit 1 is evaluated, since it is one, the bottle is processed and then inspected, it passes so a value of 1 remains (good bottle). Index machine, and use BSL to move the 1 from bit 1 to bit 2, the value of bit 1 is evaluated, since it is one, the bottle is processed, it then fails inspection and a value of 0 is written to bit 2. Index machine, and use BSL to move the 0 from bit 2 to bit 3, the value of bit 3 is evaluated and since it is a 0, no action taken (bad bottle). When the bottle gets to the final stage, since it has a value of 0 (bad bottle) it is rejected. While we were following this one bottle, others were entering the same machine and going through the same steps. So when we shifted the 1 from bit 0 to bit 1, another bottle's value was written to bit 0, so that each time a bottle shifts stations, it's status bit follows along. Using one register you can have upto 16 different stations. If you need more than that it gets a little complicated. Hope this helps, like I said, I'm a little rusty with the bit shift instruction and your actual PLC code will vary, you will have to work out when to trigger the BSL and how to handle start up and shut down. What to do if you have power failure in the middle of a step etc... Ken

Is this a software or hardware project? Do you have to build a working model of something that utilizes a PLC for control of the system? Or, do you just have to do the software part?

Only connect one end of the shield to ground. Many times grounding both ends introduces "noise" to the system. Ken

Try this site for PNP vs NPN http://www.patchn.com/npnpnp.htm

I have two Sun workstations that are part of a DCS system. Each workstation has a SCSI interface DDS3 tape drive. I use this drive to make complete hard drive images (dump command). Now.. I must send the backup copy to another site, and would like to keep a copy on hand. Making another backup is not an option, because that requires a shut down. So using solaris operating system is there a way to copy the tape from workstation 1 to workstation 2 via ethernet? Each one of these machines has two ethernet ports, one for control, and one for misc. I will be using the 2nd ethernet port, so network traffic isn't an issue. thanks, Ken

I know the dip switch is the problem, but just in case. Scaling example, the following scales an input from a NI4 for 0-100%,

Here's a clip from the 1771-IFE manual:

If it only takes 60 seconds to empty the hopper, then why do you want your PV in units per hour? Shouldn't you be using units per second instead? You could take your rate per hour set point and derive the rate per second from that. Since your setpoint is exact, there would be no error multiplication. Then do your controlling at the rate per second level and you remove a lot of the error magnificaton. Doesn't make sense to me.

I've done something similar for loss in level to determine flow rate. What I did was: 1. Take a sample every second, and determine the difference from the last sample. 2. Store this value, in an indexed array. I saved sixty samples. 3. Average the sixty samples, this helps minimize noise, bad readings etc..., this will give the average rate per second over the last minute. 4. Multiply the average rate per second X 3600, which will give you the rate per hour. 5. This rate per hour can then be used as the PV in your PID. A lot depends on the response of your system. I have found that the longer time between samples gives the smoothest system. But, if it is a system with rapid rate changes, the longer the sample time the greater the response lag. Once you have the logic in place, you can play around with the timer value to "fine tune" the system, use an N7 register as the multiplier, in my expample above the 3600 would have been in N7:0, then you can easily change the value while the logic is running. The N7 value will be one hour divided by the timer preset. I have used this in some systems that had very slow response times, and used 10 second sampling, never had very much luck with sample times less than one second. Ken

TI plc's scan thier logic from top to bottom, left to right. After the end of the scan the outputs are updated. So if two instructions are addressing the same output (which is not recommended), the last one in the scan will always win. The output will be updated to the last scanned value. You should have your drum output tied to coils, and then use the coils to drive the physical output. Then you can use conditional logic to select which coil has control ie....If drum1 active then C1 drives Y1 if drum1 inactive and drum2 active C2 drives Y1 etc... Ken

I've used a Banner vision system for the same type of thing. Had to determine label was right color also.

Try this link to another forum at an electronics repair company, it may be what you're looking for, or they may be able to make one: Cable Link

Ron, He may be using a SLC (series C). Just in case, here's a link to the AB knowledgebase on SLC BTW/R. http://domino.automation.rockwell.com/appl...95?OpenDocument Ken

I think you will find that thermocouples are the cheapest sensors. However, they can be a pain to maintain. Since they operate in the millivolt range, a slightly loose connection can drive you nuts. I usually use omega for thermocouples: http://www.omega.com/prodinfo/thermocouples.html If you decide to use the thermocouples, then your best bet would be a thermocouple input card for the SLC. You can buy a used (with warranty) 1746-NT4 from www.plccenter.com for about $475.00. You may be able to find one on EBAY for less, I did a quick search on EBAY for 1746-NT4, and found several for around $200-250 each. Generally speaking I buy used stuff for work, and EBAY is too much of a gamble. PLCcenter offers a warranty, and we have been doing business with them for several years. Hope this helps, others may be able to give you better advice. You can also try this forum: http://www.plctalk.net/qanda/ There are a lot smart people there also. Ken