Reading UDINT with Monitor Pro 7


Thread Starter

Daniel Rallo


I'm developing an application based on Monitor Pro V7.0 (USDATA Factory Link) and Momentum Ethernet PLC's. I'm using OPC (OFS driver V2.5).

Does anyone know if there is any possibility to read 32 discrete inputs from Momentum in a lonely UDINT variable just for decreasing communication tag number?

We've already tried and it works properly except but We have a problem with the msb bit. If this bit is "1", it means the rest of bits from this variable change all its values, of course it's an effect of two's complement conversion, just
because the OFS or MPRO always works with signed variables. Is it possible working with unsigned long integer variables (32 bit) in OFS and MPRO7 ?

Did someone achieve this effect with good results?

Thanks for the replies.

Daniel Rallo
EMTE Sistemas, S.A.

Mike Boicescu

Negative and real numbers conversions are always a major pain!!
Frankly, I've done this in LookOut (National Instruments); the problem may lie in OFS, i.e. the way it converts the UDINT into "Windows"
variables. If it does not have a capability to work with "unsigned", then check whether it can work with "long", i.e. 64-bit variables; if
possible, read the UDINT as LONG INT; the high-order 32 bits would be 0, which makes them "positive".
If this does not apply, then the only way is not to use the MSB, i.e. to leave it zero; thus, the variable is positive and stays unchanged.
Another way is to try to use a general purpose OPC. I used successfully OmniServer from Descartes Systems Sciences, Inc. ( "" ), which can be configured for ModBus serial or TCP/IP (but not ModBus Plus, because it does not "know" the Hardware), and does not convert