SLC 5/05 to 1770-KF2 Module

[power_plcdummy]

I am replacing an AB SLC 5/04 with a 5/05. The existing connection from the 5/04 connected to the KF2 via DH+ to talk serially via DF1 protocol. When I replace the 5/04 PLC with the 5/05, how do I connect the PLC using the serial port to the KF2 module? Is there a serial converter cable available?

 

[Operaghost]

So I think a little more detail is needed as I am confused.

The SLC-5/04 has DH+ built in to it. Plus it also has a serial port. The 5/04 wouldn't need the KF2 to get onto DH+. What was the KF2 connected to through the serial connection?

The 5/05 has built-in Ethernet and a serial port. To access the DH+ is would require the KF2 be connected via its serial port. That makes sense.

I'm guessing I am missing something here. Can you give us a little more info on the devices being used and how they are connecting?

OG

 

[power_plcdummy]

Sure thing and thanks for the response. Sorry - I am 100% NOT a PLC guy by trade. So the existing 5/04 uses DH+ out to the KF2 box. The KF2 box appears to exchange the DH+ to DF1 which the end DCS control system uses. The end system (ABB DCS) talks DF1 serially. I'm replacing the 5/04 with a 5/05. So, how do I get the ABB DCS which talks DF1 serially to talk to the new 5/05? I assume I need the KF2 box still or can I connect directly to the 5/05 serial port and simply configure the PLC. Thanks again for any information.

 

[Operaghost]

The 5/04 and the 5/05 have serial ports that talk DF1 natively. So it would be possible to go directly from the DCS to the serial port of either of those controllers.

Now, since they didn't do that, I am guessing there must be a significant distance separating these devices. If that is the only reason why they used the KF2 then what we really need is a way to get more distance from the serial connection which usually tops out at about 50 feet. There are serial to Ethernet extenders that can extend that distance to maybe 1,000 feet. But this requires a device at each end to convert back and forth between serial and Ethernet.

Or there are serial to Ethernet converters that can convert the serial data so it can be received on the Ethernet port of the 5/05. Probably the better option.

I'll let others jump in with their solutions as I don't have much experience with these products.

OG

 

[power_plcdummy]

Good point and yes, the distance between the PLC 5/04 w/KF2 box (soon to be 5/05) and the DCS is probably 250-300'. The cable leaving the KF2 box gets converted to fiber via a Black Box Modem and then goes fiber to the DCS where it converts back with another Black Box modem to the DF1 serial connection to the DCS. Honestly, I have no idea what that KF2 box is doing.

 

[JaxGTO]

Seems like you could go Black box serial/DF1 right to the SLC 5/05 serial port. Only problem would be if there are other devices on that DH+.

Does the Blue Hose (DH+) go anywhere else other than from the KF2 to the SLC 5/04?

 

[chelton]

Good point and yes, the distance between the PLC 5/04 w/KF2 box (soon to be 5/05) and the DCS is probably 250-300'. The cable leaving the KF2 box gets converted to fiber via a Black Box Modem and then goes fiber to the DCS where it converts back with another Black Box modem to the DF1 serial connection to the DCS. Honestly, I have no idea what that KF2 box is doing.

Is the 5/04 the only device on the DH+ network? Are you sure there are no other devices on the network the DCS is communicating with?

 

[Ken Roach]

When I used to do migrations that involved DCS serial interfaces, I insisted on capturing and analyzing thoroughly the actual serial traffic. There are all kinds of gotchas and legacy stuff that can be very difficult to find and very unpleasant to encounter during the switchover.

It's a little funny that the DH+ cable (the blue-jacketed twin-conductor to the SLC-5/04 network port) sounds like it is short, and they converted RS-232 to fiber to reach the DCS. DH+ from a 1770-KF2 would be at 57.6 kb/s, which can run 10,000 feet on that cable. Physically run down that DH+ cable to see if it runs off to other A-B controllers.

It is very likely that the DCS is using serial commands that could be easily swapped to the onboard RS-232 serial port of the new SLC-5/05.

The SLC serial ports can support the same "PCCC" protocol commands over the serial port as it does over the DH+ port. That includes native SLC-500 commands, and most PLC-5 commands, and the most common PLC-2 commands. You really don't know what the DCS is doing until you intercept and analyze it.

 

[JesperMP]

Maybe the original designer could not connect to the CH0 RS232 port because it is or was in use already.

Is this correct ?
[SLC5/04-CH1] --(DH+)-- [KF2] --(RS232)-- [RS232/Optical extender] --(fiber)-- [Optical extender/RS232] --(RS232)-- [ABB DCS].
If so, yikes.

You should investigate if you could change over to Ethernet from the ABB DCS.
You would then simplify the above and also get much much better performance.
[SLC5/05-CH1] --(Ethernet)-- [ABB DCS].

I think that there is a good chance that even legacy ABB DCS system supports Ethernet to AB PLCs.
If not, Does the ABB DCS support OPC ? If so, simply use RSLinx as OPC Server for the Ethernet connection to the SLC5/05 PLC.

 

[Ken Moore]

I worked on a FoxBoro I/A DCS that had a similar layout. The DCS only spoke serial, so a KF2 was used to get on the DH+, with the plans of adding more DH+ nodes in the future. Over the years, two more DH+ nodes were added.
So... maybe they were planning for multiple nodes, but never needed the extra capacity.

 

[power_plcdummy]

Thanks everyone for the awesome responses. Not being a PLC guy makes this difficult for me so your feedback is welcoming. So the 5/04 is the only thing talking DH+. The new 5/05....I'm hoping I can use the ethernet port to talk to the HMI's and the serial port to talk to existing DF1 network of the DCS.
The reason for fiber is the room where the PLC is in a separate part of the facility than the room of the DCS system. Fiber was run -thus the fiber conversion after the KF2 box. I'm not even sure what that KF2 box is even doing to be honest. Not sure if it's for distance or for comms conversion. I wish i could attach a photo - i have a great diagram.

 

[Ken Roach]

You're doing all the right things asking these questions ahead of time.

If the SLC-5/04's serial port (called "Channel 0", the DB9 male connector toward the bottom of the CPU) is not plugged into anything now, you could experiment by making an adapter cable and just moving the DCS connection from the KF2 to that port. If it works with the SLC-5/04, it will also work with the SLC-5/05: their serial port functionality is identical.

My guess is that the designers were planning on connecting the DCS to multiple A-B controllers, or they had a manual that showed how to connect via a 1770-KF2 from back when A-B controllers didn't have RS-232 serial ports (before about 1988).

You can figure out the serial configuration of the 1770-KF2 from the DIP switch settings on the module. There is no software/nonvolatile configuration, it's all hardware set.

The packets the DCS is sending to the -KF2 will have a destination "Station Number" on them, which is equivalent to the DH+ Station Number of the target device. DH+ is some old stuff; there are sixty-four possible Station Numbers but they're numbered in octal, 00 through 77.

It's likely that the SLC-5/04 is set for DH+ Station 01, and the DCS is addressing its DF1 protocol packets to DF1 Node 01. So all you have to do is configure the Channel 0 serial port to also use DF1 Node 01, so it reacts correctly to the incoming serial packets.

You can get an idea for the diversity of command code support among A-B controllers from the 1770-RM516 DF1 Protocol Reference manual in the table on pages 7-2 and 7-3.

Because the SLC is the target of the messages already, it will almost certainly support all the commands being sent by the DCS via the 1770-KF2 if those commands come through the serial port instead.

I give the DCS a <5% chance of trying to read diagnostic data directly out of the KF2, which wouldn't be reacted to by the SLC serial port and would give you some headaches.

This is the part where I mention that if you're going to do serial analysis work on legacy systems, the best money you can spend is on a Stratus Engineering EZ-Tap.

Even if you don't also spring for a Frontline Test Equipment analyzer software suite, being able to know for sure what's on the serial line instead of squinting angrily at blinky lights is a game-changer.