Interfacing Honeywell HC900 with Allen Bradley 753 Drives

jazalex2002 · Jul 18, 2014

I am currently in a project where I need to interface a Honeywell HC900 Controller to a Allen Bradley PowerFlex 753 drive via Ethernet. I have a 20-COMM-M Modbus /TCP adapter installed in my drive. I'm using a Modbus Slave Function Block in my Hybrid Control Designer software to communicate with the drive via Ethernet. This function block has the ability to read from the drive using function codes 3 or 4, and write to the drive using function codes 6 or 10. Allen Bradley wants me to use Function codes 16 and 23 in order to write to the drive speed references. The Honeywell Controller only has the ability to write to registers using function codes 6 and 10.
Does anyone know if there is any possible way to accomplish this with the equipmnet I have?
I am able to select preset speeds, but I cannot write to the speed reference parameter. I would also like to be able to read the Motor Current, and the motor speed, but I need to be able to read the High and Low words of the drive
Any help with this would be greatly appreciated.

danw · Jul 18, 2014

Life lesson - is it decimal or hexadecimal?

decimal 16 = hexadecimal 10 = write multiple registers
decimal 06 = hexadecimal 06 = write a single holding register
decimal 23 = hexadecimal 17 = read/write multiple registers.

The HC-900 supports 06h, 10h for writing single or multiple registers. It supports 03 which reads single or multiple registers.

It does not support 17h, but many devices do not support 17h. The task that 17h does can be done with 03 reads and 06h/10h writes.

The HC-900 supports 16 bit signed or unsigned integers and 32 bit IEEE floating point. I'm not sure whether it can interpret 32 bit long integers.

The HC-900 Modbus manual is HC900 Process Controller Communications User Guide, 51-52-25-111, September 2013, Revision 11.

It's somewhere on their site under the documentation tab (expand "items per page" and look under "public support documents". Their search engine is near useless.

https://www.honeywellprocess.com/en...00-control-system/Pages/hc900-controller.aspx

JHarbin · Jul 18, 2014

jazalex2002 said:
I am currently in a project where I need to interface a Honeywell HC900 Controller to a Allen Bradley PowerFlex 753 drive via Ethernet. I have a 20-COMM-M Modbus /TCP adapter installed in my drive. I'm using a Modbus Slave Function Block in my Hybrid Control Designer software to communicate with the drive via Ethernet. This function block has the ability to read from the drive using function codes 3 or 4, and write to the drive using function codes 6 or 10. Allen Bradley wants me to use Function codes 16 and 23 in order to write to the drive speed references. The Honeywell Controller only has the ability to write to registers using function codes 6 and 10.
Does anyone know if there is any possible way to accomplish this with the equipmnet I have?
I am able to select preset speeds, but I cannot write to the speed reference parameter. I would also like to be able to read the Motor Current, and the motor speed, but I need to be able to read the High and Low words of the drive
Any help with this would be greatly appreciated.

I'm not sure how much help I will be - I typically *use* Modbus/TCP with the HC900 (hundreds of communications installations) more than I *remember* the function codes.

However, the HC900 can both read and write the two words (high and low)that make up 32 bit floating point registers and 32 bit integer registers. If you can't read and write what you are looking for it *could* be the byte order or the word order. This is fully adjustable in the HC900 Modbus/TCP Slave Block.

It also reads and writes both 16 bit UINT and INT registers.

If someone asked me if I could interface an HC900 to an AB Drive with Modbus/TCP, my answer would be I can't see any reason why not. I haven't done so with an AB Drive, but I have with others.

jazalex2002 · Jul 21, 2014

Thanks very much for the help.I am able start and stop the drive with no issues and select preset speeds, but to write directly to the speed reference in 32 float or unsigned I cant' seem to get it work. I wouldn't think I would need to change the double register format since things seem to work when I select preset speeds etc. I'm also unable to read the drives speed, current etc. in the logic status word. I've attached some of the AB manual pages that pertain to this.
I've been working with HC900's for some years now but I haven't had a need to use Modbus TCP/IP slave blocks until this project. Please be patient with me as I am learning on the fly! Once again, I greatly appreciate the help form the forum members

JHarbin · Jul 21, 2014

jazalex2002 said:
Thanks very much for the help.I am able start and stop the drive with no issues and select preset speeds, but to write directly to the speed reference in 32 float or unsigned I cant' seem to get it work. I wouldn't think I would need to change the double register format since things seem to work when I select preset speeds etc. I'm also unable to read the drives speed, current etc. in the logic status word. I've attached some of the AB manual pages that pertain to this.
I've been working with HC900's for some years now but I haven't had a need to use Modbus TCP/IP slave blocks until this project. Please be patient with me as I am learning on the fly! Once again, I greatly appreciate the help form the forum members

Having the wrong word order in floats or 32 bit integers can still be a problem even if there are no problems with 16 bit integers.

From looking at the manual, I am going to *guess* that it is a 32 bit integer. the starting register is 10003 so make sure you convert that to hex and set that to the Modbus/TCP register and configure it as 32 bit integer (don't know if it is signed or unsigned). When you convert to hex, you will most likely need to subtract 1 so convert 10002 to hex. By my quick check, you should use 2712 in the slave block.

Try all 4 register formats before attempting something else, but if this doesn't work, try 2713.

After trying this, you should be in the neighborhood and should be able to figure out what is wrong.

Keep in mind that you will have to do scaling in the HC900 to convert the values you read or write either from engineering units to 32767 scale or from 32767 scale to engineering units.

Allen-Bradley, what are you going to do...

Interfacing Honeywell HC900 with Allen Bradley 753 Drives

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