Are 32Bit Reads (Double Word) Combined ?

[dcharv]

Hi,

I am communicating with several PLCs using modbus TCP.

I have a number of channels for each PLC that read 32 bit registers

I/O type : Read Holding U32(3)

As these are double words, the addresses are not sequential, but rather having a step of 2 (for example 1530, 1532,1534 ...)

Are these reads combined by DF or are they executed separately ?

If they are done separetely maybe its better to write a sequence and do the reading using modbus device functions.

thanks

[AzeoTech]

If the channels are sequential by two with a U32 I/O type, DAQFactory will combine the queries. You can test this yourself. Just create a new document with just two channels, say 1530 and 1532, with a timing of 1, then look at the comm monitor. You'll see one query every second requested 4 registers, which get combined into the two channels.

[dcharv]

ok, thanks ... no need to write extra sequences