tingxing

Hello,  My PLC is connected to PC using ethernet port, and the PC is requesting data (DMs) from PLC to do data logging. I want to know if it is possible to check the latest TCP communication request's time stamp. As a kind of something like handshake, so I can be sure the PC is still working. Does Mitsubishi's PLC keep this kind of data anywhere? Thanks in advance. Ting      

  Basically it does not matter if doing send/receive multiple times or once in a single command. But, I found at my computer, reading a DM takes about 50ms, with baudrate of 38400bps.      for 50ms, it should have been processing:  50/1000*38400= 1920bits ~192bytes  ~ 40words So, it is reasonable to expect to be able to access much more DMs (or other words). So I am trying hard to be able to send them in a single send/receive to speed up performance.   Hope this helpful for others and welcome much more advice too.   Ting    

  I read in a manual (W227E12_FINS_Commands_Reference_Manual.pdf) that there seems to be a command capable of doing such task. Trying to use such kind of command is based on expectation of performance improvement:            for example, communication time of three times of reading: DM200, CIO3600, CIO 4000                         50ms + 50ms + 50ms -> 150 ms            but reading once, might be only: 100ms        -> this is not expectation, but I guess there is really such performance merit, and would like to measure if possible.   Ting    

I purposefully avoid changing PLC. -> we use personal computer to communicate with PLC to sample some of the DM, CIO etc device's status.     Changing PLC is a good way to do it efficiently, but this incurs extra work and possibility of mistake. and further more, you need to be on the site to do the change, while updating a PC's program need not.

Thank you for your suggestion. After reading parts of the manual, I also began to realize this. Probably,  FINS command should be used (?).   Ting

  Hello,    I am using Hostlink protocol to read data from PLC units. for example @00RD22220001..., will return DM2222's value. But I want to know, if I could read multiple DM values at the same time. for example: DM2222, DM3000, DM4000, reading these DMs with one communication. Please note that these are not continuous DM areas. I know a sequence of DMs can be read by specifying starting address and count.   Many thanks in advance.   Ting              

cause of the problem might has been clarified:       too much current is found to be flowing through the safety relay - a calculation mistake, we should have chosen a relay type of higher specification. To clear the problem, we changed the relay to a contactor.   Many thanks for the helpful suggestion. Ting

  Hello,  I want to know, if it is worthwhile to transfer from Q series to iQ-R? Currently our equipment is using Q series, which ss a vacuum coating equipment with about 10 power instruments, 20 gas controllers, and pumps and so on. As for the analog and X, Y points, Q is quite capable.   I can not see any advantage to switch to iQ-R, but some people want to. So I want to know,       1. will Q be outdated in the near future?       2. will use iQ-R cost much more than Q? including peripheral units.       3. has iQ-R really been widely adopted?       4. thoug iQ-R may be powerful, I think use multiple middle size CPU's can be more advantageous,              is this right? Many thanks in advance. Ting    

  The safety relay is supplying 24V power line for CC-Link modules, and Emergency Stop circuit.  

Thank you very much for the advice. This relay is being used together with Omron's safety PLC, G9SP. I am also wondering, if my logic is something wrong. This symptom happened after the circuit had been being used for quite several weeks. Then suddenly... I try to extract the circuit for a clear check purpose.   Ting  

Hello,  I am using Omron’s safety G7SA to relay 24 volt line. But the strange thing happening is that, one relay’s output is only 5 voltage, even the relay is on. I exchanged relays, it remains the same. Maybe the base socket is problematic?  Or is this just G7SA failure? 5v (exactly 4.96v) is strange. Please give me some advice.   Many thanks in advance.   Ting    

Thank you very much for your reference link. I am not sure, but what I got is not so quick: 10 points per 30ms. what I got seemed to be limited to an interval of 30ms.  The attached file is what I took from oscilloscope, which I output interpolated value from table by using SCL instruction. Though the table has about 10 points to describe Sin curve, it should not have been so coarse as what is shown in the picture. The picture apparently shows the limit of 30ms.   I  have checked scan time, which is 2-3 ms, and D/A's specification is 1ms/channel, so the limit might be bottle-necked at somewhere else ... Ting Xing  

Hello,  I am trying to generate a wave form, such as sin, using mitsubishi's LCPU. The problem I met is that time precision of the wave form generated is only about 30ms. I checked my cpu scan time is about 2-3ms. my DA conversion specification is 1ms/channel. I am afraid CC-Link communication delay is the cause, but not sure. From the wave form, it seems some where time division is limited to about 30ms. I have expected at least for example 10ms can be obtained, i.e. if the period of my wave form is 100ms, I can output and get at least 10 data points. Would anyone give me some advice. Many thanks in advance. Ting Xing  

Really easy? That will be quite assuring. Thank you for the manual and comparision of A and Q series. In Omron world, we ever used Loop Controller, which might be over-engineering, I think. Ting

Hello, I have ever implemented PID control in Omron's PLC using its PID instructions. (thanks to the help of Mr. PLC's posts) Now I want to know if it is equally functional under Mitsubishi's PLC cpu's? Is the code complicated? Because I might only need one or two PID control loops, the processing overhead for CPU is negligible, is it right? Many thanks in advance. Ting