Subnetwork problem with the AB7007 gateway
Hi All,
I have been using Anybus gateways for quite a few years now in my industrial automation products. The product in question uses RS485 signaling, the protocol is proprietary, and is composed of bytes. I have attached the log file below.
I am now stumped with a problem that I cannot solve.
The subnetwork LED no 5 (Subnetwork Status) becomes red, just when a transaction is sent by the gateway to my RS485 based device connected to the subnetwork. I used the log feature and obtained a log of the transactions.
I notice that the transactions sent and received are all correct. Moreover the device receives transactions from the gateway perfectly, even though the Subnetwork status LED is red.
I understand an error like would happen if receive packet does not match the Response format. However the log file indicates the response is correct, this indicates the problem could be something else:
Could anyone please suggest what I should do??
Hardware Details are as follows.
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Gateway Type AB7007
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Serial device- stepper motor (trinamic motor type: PD57-1-1161)
This is the device in question https://www.trinamic.com/products/drives/pandrives-details/pd5760-x-1161/
The protocol details are given here (please see Reply format section) https://www.trinamic.com/fileadmin/assets/Products/Drives_Documents/PD-1161_TMCL-firmware_manual_Fw1.42_Rev1.08.pdf -
The connection is RS485, baud 19200, N,8,1. The cable is 5m long.
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Fieldbus is EthernetIP, I use a web browser, and send commands, I have used the IXAAT Ethernet IP test software.
Config files for the gateway are given below.
thanks
a
Trinamic-v2.cfg (16.0 KB)
Trinamic-v2.cfx (914 Bytes)
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Hello,
I do not see the log attached but it sounds like the timing could be off. Try adjusting your message delimiter.
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Thanks for reply:
Please see log file:
Could this be because of long RS485 lines (5 meters)?, also the stepper motor +24VDC and Ground are running with the RS485 lines (5 core cable).
I have also not put a terminating resistor across the RS485A+ and RS485B- lines, would this be required ??
log2.txt (4.5 KB)
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Hello,
Looking at the log you are seeing RX and TX data this so it does not looks like an issue with the BUS. The query and response looks good. Do you see any data in the node monitor? Have you adjusted the message delimiter? It still looks like that is the most likely issue.
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Hello,
I have modified the wiring, previously the +24 VDC and Ground were running alongside the RS485 lines. I have separated the power and the communication lines.
Could you recommend any suitable RS485 cable that will be good for the gateway?? The RS485 cable should be at least 5 meters long.
Do you think an ethernet cable cat5 would be good for RS485 communication with the anybus gateway? The ethernet also has twisted pairs inside which should be an advantage.
thanks
a0 -
Hello,
I don't have any recommendations for cables but for a run of only 5 meters CAT 5 should be good. Here is a article I came across that might help. https://www.maximintegrated.com/en/app-notes/index.mvp/id/3884
That being said your issue is not from the signal, rather it has to do with the software configuration. As stated previously it looks like the message delimiter might be to long for how quickly you are sending messages. Have you tried adjusting this?
Deryck
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Hello,
Thanks for the link.
In answer to your query wether any data was received in the Node monitor:
No data is being received, although the gateway is able to send data. By tweaking the Timeout, retries and Reconnect times I was able to receive data, however this is not always consistent.I did change the Message delimiter however this did help the situation, rather it slowed down the transmission. I used a setting of 2, 3, 4 etc. The higher the value more the delay in transmission.
In the attached configuration file, the first transaction works better, the subnetwork is able to recover from the fault condition, however the second transaction does not perform well.
From the log file I can see the transmission is being repeated several time by the gateway, I believe this is because the gateway is not receiving the response correctly, however the log file indicates data received is correct.
Could the transmission be "bouncing' due to line resistance??
thanks
aCAL-v4.cfg (16.0 KB)
CAL-v4.cfx (1.6 KB)log.txt (4.5 KB)
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Try setting the sub network timing message delimiter to 90 then try 100, 200 etc
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Thanks for the help.
Unfortunately the problem was not in the settings at all, it was the bias resistor and the terminating resistors, I assumed the serial device would have biasing on the RS485 lines. After adding the bias resistors (470 Ohms) and the terminating resistors (120 Ohms at both ends). I am now able to get a good transmission.
Just another question:is it OK to use the +5 VDC on pin 1 (subnetwork connector) to pull up the RS485+ line of the bus?? The bias resistors are 470 ohms. I also used the signal ground to pull down the RS485- line via another 470 Ohms.
thanks
a0 -
Hello,
This is a bit surprising typically is if there is a noise issue you will not see any data in the log. Perhaps when you took the log the issue was not present.Yes, these pins are designed for this, you should have 5V between Pin 1 and pin 5.
Deryck
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