FX3U or Q series

[ianbuckley 0]

I have been asked to replace an old A1S controller on a machine with a newer Mitsubishi controller. The old system has interposing relays, a bunch of indicator lights and a contactor. The project is to update to a touchscreen, a VFD and a new controller. We have used the E540 and now the E740 drives using analog control for many years. We have only used Mits PLCs a few times: a couple of A1S in the mid 90s (to be replaced here) and a few FX1s bricks for a really simple application. I have never used a Mits HMI. For this type of machine, I have used a CompactLogix/PowerFlex/PanelView Plus from A-B or S7-200/MM420/MP277 from Siemens. These designs use communication links for the VFD setpoints and to the HMI. I would like to propose something similar using Mitusbishi parts. The local Mitsubishi contacts have pointed me toward the Fx3U or the Q series PLC, a GT15 series HMI and the E740 with a communication adapter. The application requires 32 inputs, 16 outputs and communication to the VFD and the HMI. 2 of the inputs require reaction to state change in the 1-2ms range. 1 of the outputs should be controlled to ~1ms resolution - meaning I can read an input and create a variable delay between that input and the output energizing in ~1ms increments for a critical timing function. Obviously the A1S with interposing relays cannot do this function properly, but it would be good if the new controller can. Our local distributor initially suggested the FX3U, but the area rep from Mitsubishi suggested we might need to step up to the Q series for the 1ms throughput of the precision timing signal. The catalog seems to suggest the FX3U could do the job, but I would like to check and see if the Mr PLC community knows of any potential pitfalls in choosing the FX3U over the Q series for this application. This could very well be a one-off project and I would like to make it as painless as possible. Thanks for any advice, Ian Edited 4 May 2011 by ianbuckley

[kaare_t 155]

For single machines/projects I almost always use a Q PLC. The reason for this is that the possibilities are "limitless" in case you figure out you need a function while in the middle of the project, or after the project. In essence it almost always saves engineering time since you can simply do/program exactly what you want, while with the FX-series you might have to do time consuming work-arounds. If you are talking about several identical machines then you can justify the added engineering time with the low cost of the FX-series, but once again; if it's one machine I would go for the Q-series. Just my opinion.

[plcdp 11]

Hello, I have some machines here that were originally using the FX3U PLC. I ran into problems with some time critical functions. I was however able to work around with the built in input interrupt function, but on the newest machine I upgraded to a Q02H PLC. BIG difference. The program was scanning at 30+ milliseconds on the FX. The same program transposed to the Q series scans at .7 milliseconds! Hope this helps. ps I also used to use the GT15 series HMI's, and I have since upgraded to the GT1665M HMI. It has all the same features and functionality, but also has built in ethernet and is 300-400 dollars cheaper than the one without the ethernet. plcdp

[ianbuckley 0]

This control system is pretty well defined. There are over 500 of these machines installed around the world. Of course, we are always looking to improve the control as technology evolves, but there are not a whole lot of features that are new, just better ways of doing the same thing. I have not gotten any pricing information yet. I want to avoid the ControlLogix / CompactLogix type issue, where a CompactLogix will do the job, but you can pay 3-4x the money and do the job with a ControlLogix too. It sounds like the Q02H is a much better processor, so I will at least make sure that is part of a comparison. The other issue that you kind of touched on was how to do the communication. A-B has Ethernet/IP which makes the PLC-HMI-VFD communication fairly painless. Siemens has Profibus or Profinet. It looks like Mitsubishi has CC-Link, but will also support Ethernet, Modbus, Profibus and others. Ethernet is nice for programming because the cable is standard and does not require any special interface card. However, if CC-Link makes exchanging data (~30 words with the HMI and set speed, actual speed, fault codes and maybe a few parameters with the VFD) easier to set up, I am willing to consider that also. For that matter, I have a few other controllers that I would like to interface with the Mits drives via RS232 anyway. I just haven't had a pressing need yet. So, I would welcome any suggestions for the best way to communicate also. Thanks for the input! Ian

[kaare_t 155]

Make sure you get a pricing for a "U" series CPU (e.g. Q03UDE) since they are the "newest". In addition, all the new "U" series that has the "E" in it (like Q03UDE) has a built in Ethernet port. They are also pretty "cheap" considering that you get a very good CPU and the Ethernet port. For the FX-series, you can add Ethernet support by adding the FX3U-ENET, however the FX-series does not have anything that can support ModbusTCP. When it comes to communication I would almost always say that you should use a Q-series PLC since the FX is pretty slow on the FROM/TO instructions because of the limited backplane bus. However this does not apply if you are using serial communication via the ADP modules since they mount on a different bus on the left hand side of the main unit, and don't use FROM/TO instructions. The FX CPU is pretty fast as long as you don't use too much FROM/TO which affects both communication time AND scan time! The FX-series has CC-link too, but note that the module mounts on the right hand side and will affect scan time a bit. If you could provide a small specification of what you need it would be really helpful for us to help you. Like a list of equipment you are considering to buy.

[Inntele 60]

You can use advices above or to use following configuration of PLC: FX3U-32MT FX2N-16EX FX3U-485BD This variant allow to save money extremely. FX3U-485BD serves for communication with VFD by internal commands of PLC. In case if VFD and PLC is installed in the same cabinet the abovementioned communication board is applicable, otherwise would be better to use FX3U-CNV-BD and FX3U-485ADP-MB, because the last is equipped with galvanic isolation. High-level control and PLC-programming can be organized via HMI , working in transparent mode, i.e. you connect to USB or Ethernet port of HMI to have connection with PLC. As for high-speed output, please describe in detail, what type of actuator is connected to this output and what is the task of its control should be implemented. Not excluded that the same task could be solved without usage of high-speed function.

[RheinhardtP27 0]

Good opinion. Sitting with exactly this problem now.

[Crossbow 295]

Go for L Series. It's going to be a slightly lower cost than Q, and it's the same CPU specs, with built-in Ethernet, and on the big CPU, built in CC-Link. It has 16 inputs and 8 outputs built in. Don't connect the GOT to CC-Link, if the PLC has Ethernet built in, it's far faster for lots of word data to a GOT.

[ianbuckley 0]

I tried to add a reply yesterday and it did not go through and Mr PLC was really slow for me the reset of the day. It was very strange. The output is a solenoid whose plunger needs to actuate with accurate timing. The window of actuation can be as small as 2.0ms without causing a mechanism jam at rated speeds. So I need to create a response from reading the sensor to energizing the solenoid that is repeatable within +/- 1.0ms, with adjustable increments as small as possible for fine tuning. I have requested pricing for Q series and FX3U PLC models including a few different Q CPUs. FX3U option FX3U-32MT/DSS FX2N-16EX-ES/UL FX2N-16CCL-M (or) FX3U-232-ADP-MB Q series option(s) Q00UCPU, Q01UCPU, Q02UCPU, Q02HCPU QX40-S1 QX40 QY80 QJ71C24N-R2 (or) QJ61BT11N HMI GT1565-VNBD (or) GT1665M-VTBD VFD (2) FR-E740-095-NA filters and brake resistor... I got an e-mail today from the Mitsubishi area rep. He said he recommended a QJ71MB91 Modbus adapter to talk to the VFDs and using the built-in RS232 port to communicate to the HMI. This would limit the optional hardware. I had not looked at the L series before. I don't really like the 0.1A sinking outputs, but everything else looks good. Might have to consider that option as well. Interposing relays are not the worst idea anyway. I assume the L series configuration would use CC-Link to communicate with the VFDs (with CC-Link adapters)? Ethernet to the HMI would certainly be faster than RS232, but isn't CC-Link up to 10Mbps? That would be plenty fast for 20-30 words of setup data. I will ask the area rep about the L series. On this project, I am most concerned with ease of programming. Anything new will be a huge improvement over the indicator light system being replaced, and I am not sure there will be much chance to re-use the engineering for this project. Thanks for all the help! Ian

[Crossbow 295]

CC-Link can go up to 10MB depending on distance. CC-Link would be a better choice for communication to VFDs too, since you can read/write/adjust parameters and more. You can always buy a relay output module for the L Series. And don't go near Q02H. There is no reason to use the old Q Series when the iQ Series (QnU processors) are same price or cheaper, and at least 8x faster. Also don't go GT15, there is a comparable model in the GT16 platform, and GT16 supersedes the GT15 models. If you don't need 65,535 colors, consider GT1665-VNBD 16-color lower cost model. Even GT1665M-VTBD is cheaper than the old GT15, and has built-in Ethernet. Don't build a new system with outdated products.

[Inntele 60]

Hi Ian, Let me outspeak some considerations regarding the task and the choice of equipment for its decision. I insist the FX3U will be the best choice not only in price but on time of development. As said already, FR-E740 has a built-in RS485 interface and FX3U supports special commands for communication with VFD through this port. Communication cards that embed into VFD, serves mainly for integration of frequency invertor into third-party networks. Of course, you can purchase one of these option card, but a time which will need to programming of communication with VFD does not shorter, as and money not less. Also the development time depends very little on PLC choice, though for QJ71C24 module it's even longer than with other configurations. Also you need in the several high-speed input and one high-speed output. FX3U has the necessary quantity on board both a number of special command for high-speed operation too. The best way to connect a GOT HMI with PLC is connection via PLC programming port. Add GT01-C10R4-8P cable or the similar of desired length to PLC specification and enjoy with simplicity of decision. Regarding to actuator control. Of course you can use high-speed operation for control of solenoid actuator. However as many other actuators it has a time response which usually much higher than 1ms. The time delay consist of constant part that depends on inductivity (energy stored in the coil does not change instantaneously) and variable part that depends on the backlash of solenoid core, which changes with the wear and tear. Thus delay response of the actuator will be variable and will exceed the resolution, with which you want to control of actuator. For FX3U PLC the scan time of program, written by competent programmer, does not exceed of a few milliseconds, that is compatible to the response time of solenoid... Edited 7 May 2011 by Inntele

[ianbuckley 0]

I am still waiting for pricing information from our local rep. I have no handle on the Mitsubishi PLC or HMI pricing at all. If the newer stuff is cheaper and faster, that removes any reason to use the older stuff. This is the type of insight I have come to expect from this forum and it is much appreciated. Does the iQ series have functions to easily interface with the VFD? I am looking for start/stop, drive running, fault codes, reset fault, and to read/write a few key parameters. It sounds like the FX3U does, sort of like an s7-200 to a Micromaster using USS for Siemens. As for the other issue, the timing problem is additive. Because the actuation itself has variability, I have less leeway on the variability of my control. If I have a 25 degree window I need to hit on an object spinning 2000rpm, I have a 2.08ms window. If I have variability of 2ms on the actuation itself, I have no margin for error at all in my control of that actuation. Again guys, thanks for the insight. I really appreciate it. Ian

[Inntele 60]

Hi, A separate electric control of actuators for your actuators list is a source of potential problems. The first part of the problem lies in VFD, if it operates without feedback, the second lies in PLC control of the solenoid. In such high-speed systems, where the mismatch of actuators can destroy them or cause to other unpleasant consequences, actuators should be controlled by mechanically driven (using cam mechanisms, etc.), rather than electrically. The mechanical interaction between actuators is more reliable, and cost of its implementation will be repaid during the operation of machine.

[ianbuckley 0]

This function is the stop of product flow through a running machine. The machine does not stop, just the flow of products into it. There is no reasonable way to mechanically link it to the rest of the machine. Product flows into the machine at 2000 parts per minute and if all is running well only stops 2-3 times per shift. When production does stop, this actuator must insert a stop between products in the infeed. To fit between products without damaging either of the pieces to be separated requires fitting in the aforementioned 25 degree window of a rotation that matches the line speed (one revolution per piece). If the actuator misses the timing too badly, the product is jammed in the mechanism. The loss of one piece of product is not a big deal, but the lost production time to clear the jam and get the machine running again is a problem. We have been successfully controlling this function of this machine for more than 20 years using a small local PLC manufacturer. Their PLCs have cyclic interrupts at 0.5ms (1s of uS jitter). These PLCs are typically used for high speed front ends, but the I/O count for this machine is small enough to make a separate controller for things that don't need high speed a waste. Because the manufacturer is not a big brand name, customers are not always familiar with them - though they are used for high speed front ends for other machines in the industry as well. Their pricing is reasonable, but not as favorable as it once was due to economies of scale. They also have not been able to keep up with the big boys on features of the development software. So as the big brand names get better at high speed timing, we are trying to accommodate our customer requests for specific brands. I have received the pricing and will be considering options. Thanks for all the input so far. Ian