Ziwi

Is there any reason why you can't pull down 7 registers (3120 - 3126) and just ignore the values of the 3 you don't need?

Hi Olivier I have used 2 PID routine's, one heating, one cooling and logic to select which one runs. Eg - If in heating mode and PV is above set point for a certain time, switch to cooling mode. My application is a cooling tower for a moulding shop. I have a speed controlled fan for cooling, and a bypass valve for heating. Although this system has been working ok for over a year, the changeover - heating/cooling is not a smooth one. My new approach is to PID control the fan, then the valve attempts to keep the fan speed within a certain range. So if fan speed goes outside of a wide dead band, make adjustment to valve position. I also add a forward feedback proportional value onto the PID CV to give a final CV. This improves control as the cooling tower receives large temp spikes.

Thanks Joe That clears up a few things, will give it a go!

Hi All So I'm doing a new project involving a V560 (looks good!) and 3 x SEW motor drives. The drives can be controlled by either Modbus RTU or analog control signals. In previous projects I have used the analog route for simplicity/robustness. Modbus offers some improved functionality. Having spent a large amount of time looking at Modbus in the Visilogic help files, help from other forum members and the drive documentation, I am still leaning towards analog. A basic Modbus implementation would involve 4 read/write parameters (registers 1-4) and 7 status reads (registers 5-11) (For each drive) Example: Request: [01] Drive address[03] Command [00][05] Register start address [00][01] No. of registers [94][0B] Checksum Reply: [01] Drive address[03] Command [02]No. of data bytes[00][00] Data[b8][44] Checksum. Is there a checksum function or must each string be pre conceived? Looking at the examples I see plenty of unitronics - unitronics master/slave applications. How different is Unitronics - (Other Vendor)? Examples would be good. Is it practical to suggest a standard format datatable and ladder structure so users can share datatables of various devices? This is sort of bordering on UDFB, but I didn't want to say that out loud! Sorry- as you might tell I'm a bit of Newbie in this dept. Thanks.

You got to love IT departments!

Hi. I'm wandering what the maximum amount of rows is that you can copy from datatable to datatable? I was able to get 360 rows to copy, but it wasn't working consistently, dropped it back to 250 and it seems ok. I see that read/write max is 128 in help file, but couldn't find any reference to copy max. Thanks.

Hi Team I have configured a high speed counter on a IO-DI8-RO8 connected to an EX-RC1. The counter is incrementing as the flow meter pulses (which is very slow) If I try to store a zero value to the MI assigned to the flow meter, it holds the zero whilst the condition is forced, but then reverts back to the previous value as soon as it is released. --[MB0]------STORE 0 to MI50 If I use a positive transition on MB0 I dont even see the zero. I use a HSC on a different V350 and it works great in this way as a crude shaft encoder using a proxy sensor on a toothed pulley. Thanks