DH+ and data acquisition


Thread Starter

Kirby, Brendan

Good Morning fellow automatons,

I am attempting a simple time measurement of data aquistion by a PLC-5 from a secondary device (in this case a KF2). The network (just these two
devices) is DH+.

What I would like to do is "see" a data request go out and the data come back. I'm not interested in truly analzing the protocol. (although that
would be fun too).

What I did was place a 485 to 232 on the DH+ network and monitor via Frontline test. The data that I see I would expect to contain many token
passing loops. However I get many errors that are probably related to data size and or parity which makes the data total indecipherable.

I ASSUME that datahighway+ is talking at 57.6k with 8 bits of data, 1 stop using standard 5v, high = 1 (485)logic is this true?

Any help would be appreciated

First of all, No I don't have time for this. But as the originator of the Data Highway Detective I just can't help myself. The data format on the
"blue hose" is proprietary, a balanced transformer coupled bipolar pulse sequence of dynamic gain approximately 7.5Vpeak. So RS485 will not work. If you have patience you can dis-assemble the code on the Eprom's in the Z80
inside the KF2 you got. But be aware AB has aggressively pursued anyone who has plugged into the DH directly (one company that I have worked with to the tune of millions). But again patience, within the year their patent will run
out. In the meantime buy a DH+ driver from one of the software vendors. Or if you must, wait for the Windows version of Data Highway Detective Plus.