Sremac Posted June 6, 2013 Report Share Posted June 6, 2013 It is the second time I have the same problem with AO6X analog output modules - although in the Hardware Configuration I choose 4-20mA option for the current outputs, they produce 0-20mA anyway! Norlmally I use it with an inverters set to 4-20mA frequncy reference. OK, I switched inverters to 0-20mA, but there's another issue - 20mA does not correspond with the value of 4095 in an assigned MI, but with 4080! Very odd behaviour, not a real problem to me becuse I made it work anyway, but I had to report it here. My best regards to all! Quote Link to comment Share on other sites More sharing options...
External Moderators Nacho Posted June 7, 2013 External Moderators Report Share Posted June 7, 2013 Please check the guide of IO-AO6X: http://www.unitronics.com/docs/io_expansions/io-ao6x.pdf?sfvrsn=0 Resolution at 4-20mA 819 to 4095 (3277 units) X min: 819 ( 4mA) X max: 4095 (20mA) 4080 or 4095 depends of the impedance input of the inverter, or the gain frecuency, etc. Quote Link to comment Share on other sites More sharing options...
Sremac Posted June 7, 2013 Author Report Share Posted June 7, 2013 Dear Nacho, thanks a lot for the remark you've made, somehow I missed it while reading the Guide. On the other hand, this means that the unit actually produces 0-20mA in both modes, so one has to use linearization network (or some similar calculation method) to scale 0-OUTmax in 819-4095 units instead of 0-4095. Logical question is then why there is a switch in a Hardware Configuration menu, i.e. what really changes when I change it? It seems - nothing. Also, I don't expect output current to be dependent of the inverter input impedance as long as it is within specified range. Quote Link to comment Share on other sites More sharing options...
farcry Posted April 2, 2022 Report Share Posted April 2, 2022 I totally agree. Usually I would select 4-20mA and this would mean that if I send 0 to MI register linked to OUTUT the OUTPUT would be 4mA. (NOT 0mA!!!) In case of IO-AO6X this setting have no effect on analog output. I think that this is HARDWARE BUG. BR. Quote Link to comment Share on other sites More sharing options...
MVP 2021 Flex727 Posted April 2, 2022 MVP 2021 Report Share Posted April 2, 2022 On 6/7/2013 at 2:54 AM, Sremac said: Logical question is then why there is a switch in a Hardware Configuration menu, i.e. what really changes when I change it? It seems - nothing. I've often wondered this, too, but just got used to it. It's just the way Unitronics does it and I agree that getting the full range at 4-20mA (of 4096 steps instead of only 3277 steps) would be preferable. However, you always have to check the spec sheet because some of the I/O, most notably the Snap-In modules, do have 4096 steps for the 4-20mA analog. 10 minutes ago, farcry said: I think that this is HARDWARE BUG. Not a bug, since it is clearly defined in the spec sheet. This is just their philosophy, which we can disagree with, but it is what it is. Not that big a deal really. Quote Link to comment Share on other sites More sharing options...
farcry Posted April 2, 2022 Report Share Posted April 2, 2022 Dear Flex727. I agree the range 4-20mA can easily be achieved with linearization. It's just that the option to select 4-20mA is confusing. It should be only 0-20mA option. That selecting either of those two options doesn't make any difference on OUTPUT, should be mentioned in manual. BR. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.