Allen Bradley Explicit Messaging

[Traders 0]

I am attempting to send a DeviceNet Explicit message to a GSE 560 Weight Indicator to zero the scale. But no success so far. Any help would be appreciated! I am using an Allen Bradley SLC505 processor, a 1747-SDN scanner, a 1770-KFD for communication, RSNetWorx for DeviceNet and RSLogix 500. I have created the DeviceNet network, have the GSE 560 in the scanner scan list with an I/O Assembly mapped to a processor input register. In the RSLogix 500 software, I can monitor that register to see the GSE 560 scale weight. I am using a DeviceNet network speed of 250, and see the weight change rapidly when weight is added or removed from the scale. I can upload the parameters from the GSE 560 with the RSNetWorx software, and can also, by manually editing parameter #68 in the GSE 560 parameter list, cause the scale to zero. I have logic in the RSLogix 500 software to send the Explicit Message using the M0 file. After a message is sent, there is a response message that indicates the transaction was "successful", but the scale does not zero.

[russh 0]

Hello Traders, I had something similar just recently. Allen Bradley documentation seems to have a few holes where Explicit Messaging is concerned. I would suggest using the Class Instance Editor within the RSNetworx program to determine the actual information required for your message. The Explicit Message requires a very exact format or it won't work -- as you have already found out. The transaction header will be the first 3 words of your message. The transaction body has to include 1) the Class (1 word), 2) the Instance (1-word), 3) the Atrribute (1-word) and 4) the Data. The size of the Data is determined by the data type. If you're sending a command to "zero", chances are the data type is Boolean which is either 0 or 1 -- 1 to activate. What documentation may not tell you is that a Boolean "1" is only one byte -- not one word. The transaction body has to be reported in bytes, so you add them up. Three words + 1 byte = 7 bytes. Again, the Class Instance Editor can help you with this to sort out the format your device is expecting. Good luck!

[Smoke 0]

I have not used DeviceNet for this command with a SLC but the command to tare with Profibus and a serial GSD module are the same .

[Ken Roach 194]

If you hvae the exact code and data that are in the SLC, that would help. I agree that testing with RSNetworx and the SCIA Editor is the best way to be sure the function works, before you try it in an SLC or PLC-5. Firmware Revision 10 of the SLC-5/05 has a new "DEM" DeviceNet Explicit Message instruction that makes these function a whole lot easier to use than the old "fill up the instruction block and copy it to the M0 file" method.

[Ken Roach 194]

From the GSE 650's EDS file: Param68= 0, 7, "20 a1 25 01 00 30 10", 0x0022, 193, 1, "Zero Scale 1", "", "00601 Zero Function (Scale 1)", 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0; That means that Parameter 68 is Class 0xA1, Instance 0x0001, Attribute 0x10. Class 0xA1 (=161 decimal) is Vendor Specific, but since many of the other parameters in this range are all Class 0xA1, Instance 0x0001, I think that GSE has is using it for Scale 1's parameter settings. I will have to check to be sure that the byte order is low-high on that Instance number.

[Traders 0]

SUCCESS! Thanks people! The information you gave got me on the right track. The Class Instance Editor is the place to go along with the inside information on the EDS file. I put the transaction information into an Integer file for formatting. It ended up like this (all in hex): 101 7 1001 a1 1 10 1 1= transaction ID 01= command to execute transaction 7= size of transaction body in bytes 10= service code of Set_Single_Attribute 01= node address a1= class (161 decimal) 1= instance (Scale 1 in this case) 10= attribute (zero scale - 16 decimal) 1= data (Boolean to activate attribute) I would be interested in finding out more about Firmware revision 10. Is the "DEM" in a newer version of RSLogix 500? I am running version 6.20

[TimWilborne 108]

RsLogix 500 Version 7 has it. Processor version 10 Can't find any literature on it right now but if I remember right it is very similar in setup to a CIP MSG in RsLogix 5000. Very easy to use. TW TW Controls

[RaymondGuillaum 0]

On 01/11/2006 at 4:11 PM, Ken Roach said:

From the GSE 650's EDS file: Param68= 0, 7, "20 a1 25 01 00 30 10", 0x0022, 193, 1, "Zero Scale 1", "", "00601 Zero Function (Scale 1)", 0, 1, 0, 1, 1, 1, 0, 0, 0, 0, 0, 0; That means that Parameter 68 is Class 0xA1, Instance 0x0001, Attribute 0x10. Class 0xA1 (=161 decimal) is Vendor Specific, but since many of the other parameters in this range are all Class 0xA1, Instance 0x0001, I think that GSE has is using it for Scale 1's parameter settings. I will have to check to be sure that the byte order is low-high on that Instance number.

Does anyone still have that EDS file ?   I'm looking for it for 3 weeks now!