MCM260-5AD analog input problem

[user13816]

Hi!

I have a MCM260-5AD module, I'm using it with a pixsys net200 converter, and a PC via modbus. It has 4 analog input ports. If I use 0-10V as input, everything is fine (all four ports), if I set the port to 4-20mA and connect the 4-20mA input, the values read from the device is very strange (all four port). I have a current generator and to be sure a multimeter in serial, to check the values. First at 4mA it produces the following bytes: 128 0 this is 32768 (as unsigned), but this makes no sence, because the lower limit is 0, and the upper range limit is 32767, both default. If I increase the current, nothing changes, after that about 8-9mA it jumps to ~65000 (unsigned, so it is minus i think) at 15mA it changes to 0 (decimal) and after that it increases. The same port with the same parameters works well with voltage, but not with current (everything is default, i checked, and i don't change any values, other than the port configuration 12 for 0-10V and 14 for 4-20mA, i checked with other modbus program the values are there.)
So the port using as current input behaves abnormally, not linear, and I don't know why.
There were a time, when I thought this was solved, but this week the problem reoccured. When i thougth this was resolved the method was: changed the port to voltage and gave 0-10V as input, and changed the port back to 4-20 mA with the current generator as input, and it worked as expected, everything was linear and happy. Next power up (after a month or so) the same issue, and this method not working rigth now, maybe never was...
The port is also shows 32768 if nothing is attached to the port terminals.
Anyone had similar behavior, anything else needs to be configured other than the port configuration for the current input?
Sorry for the long description, i hope it is understandable.

I appriciate any advice!
Thanks!
Tamás

[Pixsys tecnico 6]

Hi Tàmas,
the MCM260 I/O needs to reparameterized every time power on by your software using Modbus register address from 3001 to 3012 (see user guide). I would recommend you use an AI at a time for your debug, and not use the dafault upper limit range (32767), but set a real value of your sensor.

If you want follow this steps to reset the MCM260.

1. Power OFF MCM260 and disconnect all wire connections (eccept supply power).
2. Set DIP 8 ON and DIP1-2-3-4-5-6-7 set OFF.
3. Power ON, and after about 10 second Power OFF.
4. Set the configuration of the previous DIP and repeat the Modbus RTU Setup procedure.

Best regards.

[victoriabam]

Thanks for helping us out with the analog input problem. Heating and Cooling Toronto