AB Programming through DF1

J

Thread Starter

Jay Kirsch

Hi,

I have several AB5-20's and SLC503's on a multidropped telco circuit. Is it possible to program these controllers from the master PC with RSLinx using DF1 protocol ?

I was told by AB that when channel 0 on the 5-20 is set to DF1 mode the unit cannot be programmed through that port any longer. Is this true ? Are the SLC's different.

Thanks in advance.


Jay Kirsch
 
J

Jerry Miille

You should be able to do this if the PLCs are using DF-1 Half Duplex protocol and your master implements the Allen-Bradley procedures that allow peer-to-peer communication between the PLCs. In a DF-1 Half Duplex system the PLCs only send data when directed to by the master. If the master receives a message from a PLC that contains a destination address that is not the master, it simply resends it out on the network. To do programming in this type of a system you would setup RSLinx as a DF-1 Half Duplex node and put its address in the polling table of the master. Programming instructions from RSLinx will be sent to the PLCs using the peer-to-peer communications scheme.

Jerry Miille
 
Jay,

It's not completely clear what your multidrop telco circuit consists of, but it sounds like you're doing individual dialup stations with the RSLinx DF1 half-duplex Master driver.

You can program PLC-5 and SLC-5/0x controllers whose DF1 ports are set for half-duplex slave. When you have a continuously polling master (like on a radiomodem network) you can even hook up RSLinx as a DF1 slave in the remote location and program other slaves because the master forwards those packets.

But with a dialup system that might be impractical, as the DF1 driver will send as many packets as RSLinx requires, then maybe hang up and try to call the next station. That would be OK if the application was data acquisition, but the DF1 driver is now going to have to go through it's dialup list before it will come back to the station you're trying to go online with, and RSLogix will timeout long before that dialing sequence can be completed.

If this is a leased-line system you'll be in better shape. Otherwise you'll have to narrow down your polling list to just the station you want to go online with when you want to go online.

Regards,

Ken Roach
A-B Seattle
 
J
Thanks Ken,

The comm circuit is a digital leased-line (ADN). Permanent connection at 19.2 kbs.

Part of of my confusion comes from the getting nowhere trying to hook the 6200 software up to 5/20 after I set channel 0 to be a DF1-Slave. So I was not sure whether this was a limitation of the 6200 software or a general inability
to program this controller through channel 0 when set as a DF1 slave.

If I understand your anwser, with RS-Linx I will be able to program the 5/20 and SLCs on remotely.

Jay
 
E

Eric M. Klintworth

I don't know about the PLC-5/20's, but the SLC-5/03's can indeed be programmed over a DF1 half-duplex polling master network. Slower than the seven year itch, though, since every thing passes through the polling master, but it still beats driving all over the ity/county/whatever. You will have to add your PC to the master's poll list, of course. (My system was 9600 baud; I wouldn't bother trying at 1200 baud.)

Regards,
Eric M. Klintworth
-------------------------------------------------
 
J
Not only that, the only way to get to one of these sites is to take a dirt road that runs adjacent to a public golf course driving range. There is no fence between the range and the dirt road.

At about 150 yards from the tees, the road heads
up a very steep hillside. My truck (2WD) has
gotten stuck here before. Well, you get the
picture.

Jay Kirsch
 
Top