AB SLC 5/04 Connection Issues

OKAYEverybody I need some of your help and guidance again. I have a piece of equipmentbuilt around 1975, let's call it a printing press to simplify things. It hashad 3 electrical upgrades, An AB SLC 5/04 PLC add-on, wiring upgrades, functionallyadded and removed with ZERO documentation, the upgrade companies are out ofbusiness and the machine builder went out of business in the mid 80's. Ireceived a copy (months later) of what I was told as the latest PLC programfrom the machine sales broker. (enough said about that). I rewired the machineto how the PLC was/is wired. The PLC does have a program in it. I know thisbecause it goes into Run mode when powered up. I am attempting to connect tocompare the programs hoping they are the same. Since I have a copy of theprogram, I am able to look at the "Channel Configuration Settings" (seeattached pic) I am connected using the AB 1747-CP3 Cable. (no usb adapter inthe path). I have tried every driver in RX Linx and the "AutoConfigure" thing does nothing. RS Linx behaves the same with the cableconnected or not connected. My guess is that the previous owners had some sortof remote dial in modem connected via DH+ and I am trying to connect via DH 485.I could be totally wrong since I have very little PLC experience. Please help.

If it's a modern enough processor that supports DF1 pass through, the normal autoconfig won't work. You have to manually set your baud rate to match your controller. To verify DF1 Pass through, open Processor Status and check Chan0, if S:34/5 is 1, you have to manually configure the DF1 driver.

DF1 Half Duplex is almost always used in telemetry and modem applications with multiple slave devices on the link. It's very uncommon in a machine control application, even with a modem.

You will need to use the DF1 Polling Master driver in RSLinx Classic, not the DF1 Full Duplex or DH485 drivers. Since the SLC appears to be set up as Node 1, you can just add Node 1 to the poll list.

Unfortunately the old Half Duplex Master works very poorly with Windows XP/7/10, especially if there is hardware handshaking. It's worth a try, but I wouldn't spent a lot of time experimenting with it.

It might be easier to hire an experienced integrator who has a USB/DH+ interface (1784-U2DHP) just to connect over DH+, upload the program, and set the Channel 0 serial port for DF1 Full Duplex so you can use it with an ordinary serial port or a good-quality USB/RS232 converter.

It would be nice to upload the program and compare, you could buy one of our U2DHP adapters but they are out of most companies budget unless they use it a lot... I thought about doing a rental program for them PM or call me if you want to go that route, I dont see a reason to pay 1,500 for a cable to use it one time

Processor Status Pic

See attached pic of Processor Status

Maybe go to a local Allen Bradley distributor and ask to borrow their USB/DH+ interface (1784-U2DHP)? Just give them a PO in case you never bring it back and they can harass you forever on that unpaid PO. Its a good reminder to return their stuff.

When you create a DF1 Polling Master driver in RSLinx Classic, the polling lists are the second tab. Just put a "1" into the field above the Normal Poll List and click the "Add" button.

The SLC controllers had some flexibility to their communication ports and it can be confusing for inexperienced folks. But bear with us !

DH+ is the round mini-DIN port, which is jumpered internally to the 3-pin Combicon connector. You need a 1784-U2DHP or equivalent interface to connect to that.

DH485 is implemented in different ways (and is probably not involved in your controller). The old SLC-500, 5/01, 5/02, and 5/03 controllers all have an RJ45 jack on the front with DH485 protocol (it's not Ethernet and don't plug an Ethernet cable into it... there's +24V on some of the pins !).

But the SLC-5/04, 5/05 and MicroLogix controllers can also run the DH485 protocol on one of their RS-232 serial ports. That's why you see it selectable in some of the menus.

An easy test is this: disconnect any cables from the DB9 RS-232 Channel 0 serial port on the SLC-5/03.

If the "RS232" LED on the controller blinks slowly at about 1/sec, then the channel is probably configured for DH485 protocol.

If the RS232 LED stays off, or flickers briefly (MSG instructions will cause a very brief flicker during Tx), then it's set for some other mode, including DF1 Half Duplex Slave.

In response to Jim3846, will the local AB dealer really loan out cables? They are 2 blocks away.
In response to Ken's posting, With all cables disconnected, only the run light in on and dh light blinks about every 2 seconds. And I did add just the number 1 to the polling field, still did not help.

Jim3846 said:

Maybe go to a local Allen Bradley distributor and ask to borrow their USB/DH+ interface (1784-U2DHP)? Just give them a PO in case you never bring it back and they can harass you forever on that unpaid PO. Its a good reminder to return their stuff.

Click to expand...

Doubt the local will loan them out, they sell them for about 3k but its worth a shot... a better chance is they will stop by and upload the program for you, back in the day my local did not have a issue at all coming out, they would just consider it a demo and come out for a BS session and see what projects we had in the works

The slow blink of a disconnected network channel's LED is an indication that the channel is active/selected for a peer-to-peer network, but that it doesn't detect the passing of the network token by other devices.

Because the RS-232 port can be configured for DF1 (in several flavors) as well as ASCII and DH485, looking for that slow blink is one way to tell definitively that it's configured for DH485.

When I worked for an A-B sales office (and had colleagues in all of our distributorships), the price of borrowing an interface cable was a sales opportunity. Ask their PLC specialist to come in and do a quick review of the control system on this cobbled-together machine so they can themselves (or in cooperation with a local integrator) bid an upgrade to ControlLogix, or the upgrade of a PanelView or other obsolete device.

Even the guys who seldom bought things could still borrow stuff if they took care of it and returned it, and kept bringing at least an opportunity to quote or propose a sale.

Obviously sales is about relationships. It's always worth it to develop, increase, or renew your relationship with your local automation distributor.

Ok, I am now trying to understand the connection options. Bylooking at the "Channel Configuration Setting Tabs". General Tablooks to be a summary of Channel 0 and 1 settings.
"Channel 1 System" Tab looks to be theconfiguration for the top 2 plugs DH+ (the Blue Tube connector and a roundconnector) on the SLC 5/04 CPU card. If that's where or how you connect.
"Channel 0 System Tab" looks to be theconfiguration for the bottom RS 232 plug on the SLC 5/04 CPU card. If that'swhere or how you connect. I'm not clear on the difference between DH-485, DF1or ASCII.

I'm am not understanding the difference between "Channel0 System" and "Channel 0 User".

Also, I need to understand how to move forward. Since thePLC is configured DH+ according to the Channel 1 Configuration settings, andthe Channel 0 Configuration set to Half Duplex Slave which is not the most userfriendly connection method, I need to beable to connect DH+ via one of the top 2 ports. Then transfer/upload the program inthe PLC to a laptop, change the Channel 0 Configuration to ________, save theprogram than transfer/download the program to the PLC. Now I should be able toconnect via Channel 0 with my 1747-CP3 RS232 to Com port cable.

Ken Roach said:

When I worked for an A-B sales office (and had colleagues in all of our distributorships), the price of borrowing an interface cable was a sales opportunity. Ask their PLC specialist to come in and do a quick review of the control system on this cobbled-together machine so they can themselves (or in cooperation with a local integrator) bid an upgrade to ControlLogix, or the upgrade of a PanelView or other obsolete device.

Even the guys who seldom bought things could still borrow stuff if they took care of it and returned it, and kept bringing at least an opportunity to quote or propose a sale.

Obviously sales is about relationships. It's always worth it to develop, increase, or renew your relationship with your local automation distributor.

Click to expand...

I have used this relationship over the years with the local distributor. The only way it does not work if you don't buy stuff off of the local distributor. I had a few companies where they got too big with multiple offices where the support was out of not your city distributor and caused me problems with the sales rep. But they understood that I would eventually have another job some where in city so they still helped me.

But your a local end user, so use the sales angle to get them to stop by and try and see if they can upload it. Also, sometimes the local distributor will offer lunch and learns where they go over their latest equipment. This would be another opportunity to get free training.

Just remember some relationships like your local distributor is one you need to keep tabs on.

chippieboy said:

Ok, I am now trying to understand the connection options. By looking at the "Channel Configuration Setting Tabs". General Tab looks to be a summary of Channel 0 and 1 settings. "Channel 1 System" Tab looks to be the configuration for the top 2 plugs DH+ (the Blue Tube connector and a round connector) on the SLC 5/04 CPU card. If that's where or how you connect. "Channel 0 System Tab" looks to be the configuration for the bottom RS 232 plug on the SLC 5/04 CPU card. If that's where or how you connect.

Click to expand...

That is all correct.

chippieboy said:

I'm not clear on the difference between DH-485, DF1 or ASCII.

Click to expand...

The CH0 port (bottom D9F serial connector) is RS-232 electrically, but supports several different protocols. DH-485, DF1, and ASCII are different protocols. Since your PLC is set up for DF1 Slave, Ken Roach gave the best answer for how to set up a driver in RSLinx to connect to that port.

Be aware that you must get the baud rate, data bits, parity and error checking mode matched up in order to succeed. It has been my experience that if you miss one of those items, the driver won't let you go back and change it. Even if you stop the driver first, I seem to recall not being able to change those details, so I would have to delete the driver and then recreate it. It is usually on a telemetry system talking to a Micrologix 1000 over a radio modem where I see DF1 Half Duplex, and that little brick won't let you switch modes and I think uses BCC error checking.

Also, you may have to stop other drivers (if you have any) that are set up in RSLinx and assigned to the same Windows COM number.

I have successfully used the DF1 Polling master driver in Windows 7 and Windows 10 with a good quality USB to serial converter.

chippieboy said:

I'm am not understanding the difference between "Channel0 System" and "Channel 0 User" Also, I need to understand how to move forward. Since the PLC is configured DH+ according to the Channel 1 Configuration settings, and the Channel 0 Configuration set to Half Duplex Slave which is not the most user friendly connection method, I need to be able to connect DH+ via one of the top 2 ports. Then transfer/upload the program in the PLC to a laptop, change the Channel 0 Configuration to ________, save the program than transfer/download the program to the PLC. Now I should be able to connect via Channel 0 with my 1747-CP3 RS232 to Com port cable.

Click to expand...

In a SLC, it is possible to have a System and User mode that is changed via PLC code. Typically, this is done when you have an ASCII device and still need to be able to use the PLC with RSLogix on Channel 0. You could program a discrete input or any other imaginable condition to select User Mode or System Mode in PLC code. This feature is rarely used.

I would go forward by attempting to use Channel 0 and the Polling Master Driver. Be patient with it. Even after it is set up properly, it is slow. It can take a minute just to show that the SLC exists under that driver in RSLinx even if everything is set right. If you exhaust that avenue, then appropriate for yourself a U2DHP cable. Or sweet talk your local AB rep into helping out (also good advice from Ken).

Once you get online, i highly recommend changing that serial port setup to the default, DF1 Full Duplex, 19.2k baud, No parity, CRC Error checking.