Help with Serial Communication AB ML 1400 and PF 4M

Good evening Sirs,

I would like to use the serial port of a ML 1400 to send and receive data from a Powerflex 4M.

The point is, it's the first time I'll use this kind of communication and I don't know how to set the hardware and how to control it on the software.

I have to use the DB9 port of the PLC, them I presume I have to weld one side of my cable with a DB9 and the other side with a RJ45 (the connector on my PF) right?

Then, how do I communicate with it on the software. I heard about a "MSG" function on RSLogix 500 but how do I set up the comm port and how I manage the data beetween my two components.

Nowaday we use the 4 pin of the PF 4M on the power supply common and the 2 pin to control the start/stop of the inverter, but I'd like to do more such as reducing or increasing the speed of the inverter or reseting faults, things like that (if it's possible)

Thanks in advance for any help.

The PowerFlex 4-series "DSI" ports use RS-485 wiring, so you need an RS-485 connection to a logic controller.

The MicroLogix 1400 has an RS-485 connection on Channel 0 (the round connector) that you can access with a 1763-NC01 cable.

If you need to use one of the other serial ports on the MicroLogix 1400, you will need an external RS-232 to RS-485 converter. The A-B 1761-NET-AIC module works, as will most third-party converters.

There are numerous technotes and example code on the Rockwell Automation website for using MSG instructions and the Modbus protocol to read and write parameters in PowerFlex 4-series drives using MicroLogix controllers. This is part of what Rockwell Automation calls their "Connected Components" product line.

Connected Components Simple Speed Control:
http://literature.rockwellautomation.com/idc/groups/literature/documents/qs/cc-qs002_-en-p.pdf

Knowledgebase Article ID 61517: Control a PowerFlex 4 with Explicit Messaging
https://rockwellautomation.custhelp.com/app/answers/detail/a_id/61517

Correct if I'm wrong: the ML1400 has two serial ports: the mini din and the db9. I's reading the ML1400 manual and there is written that the db9 conector is a RS-232/RS-485 isolated port. Then I concluded it has two "functions", am I wrong?

Then another question: if I'd Like to comand more than one inverter on the same network. Then I give one addres to each of them and can send msgs by that addres? And the cable can't be welded by myself, with a db9/rj45/rj45/rj45... until I get the sufficient number of points to control my PFs network?

This thread over at the MrPLC forum may help also. Be sure to get the zip file at the link I provide.

But, if I'd like to use a ML1400 as I asked. When I tried to convert that ladder program to a 1400 the "M1" file is invalid for micrologix. Then should I create another type of Function File to substitute the "M1" or this type of communication isn't possible for the ML series?

And the cable: should I use a AB cable to communicate beetween them or can I make this cable by myself?

Correct if I'm wrong: the ML1400 has two serial ports: the mini din and the db9. I's reading the ML1400 manual and there is written that the db9 conector is a RS-232/RS-485 isolated port. Then I concluded it has two "functions", am I wrong?

Click to expand...

You have the port specifications incorrect.

Channel 0 is the round mini-DIN connector that has both an isolated RS-232 and RS-485 pins. To connect to the RS-485 port, use a 1763-NC01 cable.

Channel 2 is the DB9 connector that has a non-isolated RS-232 port only.

I'd Like to comand more than one inverter on the same network. Then I give one address to each of them and can send msgs by that address? And the cable can't be welded by myself, with a db9/rj45/rj45/rj45...

Click to expand...

Typically the wiring is done with a 1763-NC01 cable -> RJ45 -> RJ45 -> RJ45.

A-B sells a nice RJ45 plug with two screws for the daisy-chain wire. The part number is AK-U0-RJ45-TB2P and is sold in packets of 5.

RA Knowledgebase document AID # 105986 describes these connectors well.

I recommend using the A-B 1763-NC01 cable and those A-B connectors, but you can definitely fabricate this sort of cable yourself, especially if you are using a third-party RS-232/485 converter and Channel 2.

Don't try to convert Bernie's example program directly to MicroLogix 1400 in RSLogix 500. Just read it and learn from the addressing and logic.

Thx Ken, I'll try this one. But the harder thing for me here is to convince my bosses to buy those parts you said to me, probably they'll ask me to build these cables, but... that's OK.

The PLC part I'll try to learn as you said and convert it to my ML. As I'm new in this "network" subject I didn't imagined it was so difficult.

Thanks again.

Attached is the communication portion from one of our programs communicating with 4 PF drives. (Note: we set an error register to 255 as a 'communication fail' message trigger on our display.)

I see that Bernie's program and the AB example stuff I've looked at continuously loop through the messages that write the speed reference to the drive. I spotted a warning in the PF4M manual about not writing programs to continuously write to Non-Volatile Storage. Is the speed reference and command word not stored to NVS, or are you guys changing C307 to store these in RAM?

Thanks,

C307 [CommWrite Mode]
Determines whether parameter changes made over communication port are saved and stored in Non-Volatile Storage (NVS) or RAMonly. If they are stored in RAM, the values will be lost at power-down.
Options 0 "Save" (Default)
1 "RAMOnly"

ATTENTION: Risk of equipment damage exists. If a controller is programmed to write parameter data to Non-Volatile Stor age (NVS) frequently, the NVSwill quickly exceed its life cycle and cause the drive to malfunction. Do not create a programthat frequently uses configurable outputs to write parameter data to NVSunless C307 [CommWrite Mode] is set to option 1.

We're writing to the Modbus interface registers. These are not the same as the NVS areas. Obviously the control and speed must be able to be changed continuously in certain applications. It is accepted that these are volatile. It is the 'Modbus Addresses' derived from the parameter locations which must be protected from continuous writing.

Your first assumption is correct; the Command and Reference Words are not stored in NVRAM, so writing to them continuously does not produce wear on the NVRAM components.

Thanks guys, that made sense from the examples I'd seen, but I haven't seen specific mention of it being OK to write constantly.