SLC 5/01 communication from my PC!!

T

Thread Starter

Ting

I came across browsing the old discussion about DH-485 in SLC 5/01 in this web site (sometime in April to May 2001). It just happened that I am about to use this set-up now. I am just curious about this communication protocol. If SLC 5/01 is using a DH-485 to communicate with other devices (such as a PC with a 1784-PKTx card or 1784-KR card which has DH-485 options), is it possible to
connect it directly to the PC? Why do I need to use a device such as an isolated link coupler (or 1747-AIC) to communicate to a PC with a 1784-PKTx
card if the function of the AIC is as an isolator/splitter? And if this is a DH-485 protocol, can I multidrop this? Can anyone give me the pin configuration of the socket (RJ-45) of the SLC 5/01? I have a bunch of connectors/crimper and cables for this type of sockets (RJ-45) and if someone can send me the exact configuration of the socket, I might as well have to experiment this. Thanks in
advance..
 
A

Alan Rimmington

As you suggest the AIC is an isolated link coupler, the main purpose of an AIC is to provide electrical isolation between the network and individual devices. If the PLC and PC are reasonably close then direct point to point connection would be OK.
 
D

David Lawton

If you're using the old serial PIC box for DH-485 you need to connect via an AIC or AIC+ because the PIC doesn't provide the power and
therefore in this case you go via the AIC so that the comms has power. If you use a PCMK you can connect directly because the PCMK provides
its own power.
Hope that helps you
David
 
B
Because the DH-485 protocol is not an open published protocol. Those overprice A-B converter boxes typically convert DH-485 to the DF1 protocol. DF1 runs on RS-232. Some SLC's support the DF1 protocol on the DH-485 port, I think, but it is not well documented or supported.

Bill
 
L

Larry Lawver

Ting---


The cable pinout you seek is published in many places, e.g., General Information Document G19456 in the Knowledgebase at
"http://support.rockwellautomation.com/":http://support.rockwellautomation.com/


The physical layer for DH485 is RS-485. Allen-Bradley introduced DH485 and the SLC 5/01 during the 1980s to provide a (then) low-cost interface for networking small controllers and connecting low-end operator interfaces. I have since seen many creative and successful extensions of the RS-485 physical network.


The various A-B isolators, including the 1747-PIC, 1747-AIC, and 1761-NET-AIC, provide optical isolation and 24VDC distribution to a wide variety of automation products. If you don't need optical isolation and plug compatibility, don't use them.


The DH485 communications coprocessor products, such as 1784-KR (obsolete), 1784-KTX, and 1784-PKTX, offload network support from your personal computer. Direct connection to DH485, say, through an RS-485 card or a 1747-PIC, requires the driver to service the network from your personal computer's CPU. It's a performance choice.

Hope this helps!


Larry Lawver
Rexel / Central Florida
 
L

Larry Lawver

Bill---


The only DF1 to DH485 protocol converter that I am aware of as a distinct product is the 1770-KF3, which Ting never mentioned in his post. The inexpensive isolators he mentioned don't do protocol conversions. The expensive communication coprocessors he mentioned provide real value by offloading the network support from your personal computer's CPU to the bus card, but they don't do protocol conversion either.


Despite your bizarre claim to the contrary, nothing could possibly support DF1 (point-to-point connection) on a DH485 (network access) port. This explains the lack of documentation and support!


The SLC 5/01 that Ting needs help with supports DH485 only.


Hope this helps!


Larry Lawver
Rexel / Central Florida
 
T
Thanks for the response guys. But I think I made you misunderstood the post. I have with me 2 PCs, 1 with an installed 1784-KR and 1 with a
1784-PKTx card. I presume we all both know that these cards support DH485 protocol. The SLC CPU can only communicate with DH485, right? Now,
since both the PC and the SLC CPU has a DH485 protocol (the PC can communicate through DH485 because of the installed card), can I connect
the SLC 5/01 directly to these cards installed in the PCs? I also presume the PC is giving power to the cards to activate the DH485 link. If
the PC is now giving me a DH485 protocol because of the card and the SLC 5/01 is also giving me DH485, can I now connect it directly instead
of using units such the AIC (or AIC+)or PIC or KF3? I hope this will clear my post.


Ting
 
B
IIRC, doesn't the SLC 5/01 support more than one protocol on it's comm port. I know of people who have programmed them without a pic by making a custom RS 232 cable.

These comm options are for programming only, I guess. Only DH485 can be accessed from the ladder program.

I hope I am not blundering on this,

Bill Sturm
 
L
Ting---


Yes, that definitely clarifies your application.


While you can use published information to wire a non-isolated connection, I have to recommend that you add a 1747-AIC (with included 1747-C11 cable)
to the 5/01. This keeps you within the envelope supported by the 1784-KR and 1794-PKTX bus cards in your PCs.


Hope this helps!


Larry Lawver
Rexel / Central Florida
 
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