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Old February 9th, 2005, 11:22 AM   #1
pickerel
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Question AB DeviceNet Scanner Issue (1769-SDN)

I'm having an issue communicating between an AB CompactLogix DeviceNet Scanner module and custom slave devices over DeviceNet.

The issue is whenever I first boot up the system (plc, hmi, scanner) or when the system has been idle for some time (slave devices powered down), the scanner and the first slave that I power up fail to communicate with each other.

Basically in our product's application (new product), all the slave devices remain powered off until they are required to be on.

Using RSNetWorx for DeviceNet, I commissioned the scanner with a node address of 00 and configured its scanlist with all slave devices (nodes 11,12,13,14,21,22,23,24,31,32) in my network and downloaded the configuration to the scanner. I'm using RSNetWorx version 5.00.00 (build 81) and scanner's firmware version is 2.2. The compactlogix processor I have is a 1769-L35E with firmware version 13.21.

In my PLC applications logic I have an unconditional rung that sets the scanner's command register's run bit.

When I first boot up the system, the devicenet scanner reports an error code of 79 (transmit failure). This sounds about right since all the slave devices (10 in total) are powered down.

When I request only one slave to be on and apply mains power to the device, the scanner reports the following error codes: first 79 (mentioned above), then 76 for node 00, 76 for node 00, 76 for node 00, then 78 for each slave node, and 75 for node 00. At this point the scanner continues to scroll through the 78 for each slave followed by 75 for node 00. For some reason the scanner and slave device fail to establish communications with each other and I don't know why. The communication issue persists until I power the slave device done and then re-apply power to it, at this time communications is established.

Interesting thing is if I then power up another slave device while the communication problem is active with the first, communications is not only established between the scanner and the second device but also between the scanner and the first device.

I have reviewed the DeviceNet cable and system planning documents from AB and check the cabling installed in my system and every looks ok to me.

The total trunk line from scanner is only about 3 meters in length. Termination resistors are installed at both ends, measured 60.3 ohms across the Can_H and Can_L at the scanner. I have a dedicated 24VDC power supply for the devicenet network. The trunkline cable's shield and drain are only connected to earth at one end, the scanner end. V-from the power supply is also connect to earth at this point.

Thanks for your help in advance.
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Old February 10th, 2005, 01:14 AM   #2
Ken Roach
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As you have described, the 1769-SDN display alternates between a Status Code (values above 63) and a Node Number (values below 63).

When the 1769-SDN powers up, it will send "Duplicate MAC ID Check" messages onto the network. Usually, another node on the network acknowleges the DUP MAC ID check packet right away, and the 1769-SDN can commence to opening connections to its I/O slaves. In this case there are no other devices powered up and the 1769-SDN just keeps sending its DUP MAC ID Check packets for a few seconds until it declares an Error 79. At this point it stands by and stops transmitting and waits for something to happen.

When another device powers up on the network, it will send its own Duplicate MAC ID Check message, which the 1769-SDN will hear and acknowledge. The 1769-SDN then will begin to try to establish connections to the slave devices in its scanlist.

When there are no responses to its connection requests, the 1769-SDN shows errors 76 and 75. These are described in the literature as "no direct traffic for the scanner detected", and "no traffic for the scanner from other devices". I am accustomed to seeing Error 75 when there is literally no scanlist configured in the scanner, but it can also appear during the time that the scanner is still attempting to connect to its slave devices and has not given up on those connection attempts.

Error 78 means that the scanner has tried and failed to establish a connection to the corresponding slave device. The scanner tries twice using Group 3 messaging, and twice using Group 2 messaging, each with 1 second timeouts. This means you should have about 4 seconds in which the Errors 76 and 75 will display before the Error 78 occurs.

You didn't say if you are developing the DeviceNet firmware in these custom devices, and you didn't give any specifics about them if you are buying them from somebody else, so I can't share any specific information about your device.

My best guess is that there is something unusual about your device's powerup behavior. Does you device perform an Autobaud detection routine ? Sometimes those require a certain amount of network traffic.

Do you have a network analysis software package of any kind ? I usually use A-B's DeviceNet Traffic Analyzer, but SST's package is powerful and easy to use too.
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Old February 10th, 2005, 02:21 PM   #3
Ken Roach
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Here's an example of normal powerup behavior. I have a 1769-SDN (node 00) and a 100-DNY42R (Node 03) on a network. The 1769-SDN is set for 125 kb/s, and it has the 100-DNY42R in its scanlist.

When the 1769-SDN boots up, it starts sending Duplicate MAC ID Check packets, every 1 millisecond. It continues this, even after the Error 79 is declared, until I plug in the 100-DNY42R and it sends its own Dup. MAC ID Check packet.

After each module has checked twice to be sure that it really is unique on the network, the 1769-SDN commences to request a connection from the 100-DNY42R and queries it's Identity Object for electronic key checking.

You should see something like this on your network when you plug in the new slave device. If not, post what you do get !

------------------------------

Frame #  Time            Can Id Grp Msg ID Mac ID Size Data
8242 0000000"000999 0x407 2 0x7 00 7 00 01 00 29 7D 0F 00
8243 0000000"001001 0x407 2 0x7 00 7 00 01 00 29 7D 0F 00
8244 0000000"001001 0x407 2 0x7 00 7 00 01 00 29 7D 0F 00
8245 0000000"001808 0x41F 2 0x7 03 7 00 01 00 8C EC 0B 1A
8246 0000000"000888 0x407 2 0x7 00 7 00 01 00 29 7D 0F 00
8247 0000000"997582 0x407 2 0x7 00 7 00 01 00 29 7D 0F 00
8248 0000000"054476 0x41F 2 0x7 03 7 00 01 00 8C EC 0B 1A
8249 0000000"946199 0x780 3 0x6 00 4 03 4B 02 34
8250 0000000"995983 0x780 3 0x6 00 4 03 4B 02 34
8251 0000001"000512 0x41E 2 0x6 03 6 00 4B 03 01 01 00
8252 0000000"000672 0x41B 2 0x3 03 3 00 CB 03
8253 0000000"008338 0x41C 2 0x4 03 7 00 4B 03 00 01 12 00
8254 0000000"000705 0x41B 2 0x3 03 3 00 CB 03
8255 0000000"010282 0x41C 2 0x4 03 6 00 0E 01 00 01 01
8256 0000000"000737 0x41B 2 0x3 03 4 00 8E 01 00
8257 0000000"010099 0x41C 2 0x4 03 6 00 0E 01 00 01 02
8258 0000000"000736 0x41B 2 0x3 03 4 00 8E 07 00

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Old February 10th, 2005, 02:49 PM   #4
pickerel
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Ken, thanks for your replies.

I did not provide detail on my slave devices because they are custom devices being manufactured for us by one of our suppliers. Basically they maintain and develop the devicenet firmware for the devices.

The devices are new. I am currently developing and testing the integration of my AB logix5000 application to control these devices. It is possible that the devices are the cause of the issue.

I currently do not have any network analysis software and hardware that I can use to get on the devicenet network to monitor communications.

I tried the following today. When the communication issue is present between the scanner and the slave device (both devices network status leds flashing green) I reset the AB DeviceNet Scanner via the Scanner's CommandRegister Reset bit while maintaining power to the slave device. Once the scanner re-initialized, communications was successfully established between the scanner and slave device (both devices network status leds on solid green).
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Old April 10th, 2018, 10:36 AM   #5
Pradeepkumar
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Dear Sir
Problem:-- I'm having an issue of communicating between an AB Compact Logix DeviceNet Scanner module SDN1769 with custom slave devices over DeviceNet.

Iam Pradeepkumar From Salem,India. I am using a Device Net Scanner Module in a PLC Backplane of compactlogix processor 1769-L35E. This DeviceNet Module is connected with 4 Devicenet IOModule, 5 Devicenet Encoders and 5 PowerFlex40 Drives. Recently we got one new spare Devicenet Scanner module SDFN1769. I want to use it replacing the old one as a good working spare.

I mounted the new Devicenet scanner module in the PLC rack and connected the DeviceNet cable in its port. I downloaded the good Rsnetwork for Device net (*.dnt) file to the scanner Module. While going on Line it says other device net units(slave) wetre not configured.

During going OnLine in a new Devicenet networking, i Could find only Scanner Module alone. But if i open the Offline old Devivenet.dnt file and then go OnLine, i could see Red Missing Marks except on DeviceNet Module.

Pl tell me how to configure a new DeviceNet Scanner SDN1769 Module. Send me a snapShoot explanation file if possible. Iam under pressure... pl help me

Pradeepkumar Salem 10042018
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Old April 10th, 2018, 10:37 AM   #6
Pradeepkumar
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Dear Sir

Iam getting an Error code 79 in DeviceNet Scanner Module SDN1769 with Red LED
Pradeepkumar
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