ML1500 to Toshiba VF AS1 via Modbus RTU

[OkiePC]

I inherited a system with the Micrologix 1500 talking to 8 VFDs using Modbus RTU protocol. One of the VFDs was replaced with a Toshiba VF AS1. The others are all Schneider and all communicating fine.

The Toshiba needed a few parameters changed and now I am able to get a response when I poll a single address. The existing message logic had two read MSGs per VFD, the first a block of 9 addresses and the 2nd a single address.

Because it is a Micrologix I cannot do online edits and the pumps are all running and we need to keep it that way, but I can diddle the target modbus address in the MSG data table of the MSG doing a single register and can get a DN bit and a number back for Modbus Data addresses 0 through 9.

It appears that the Toshiba will require me to read 1 register at a time, but I have found nothing along the lines of a Modbus register map for this drive. Before I peek and poke one address at a time to build my own, I thought I'd ask if someone else has done this or has a better manual.

I am using one titled:
TOSVERT VF-AS1 SERIES
RS485 Communication Function Instruction Manual

And it is not very helpful.

 

[OkiePC]

Okay I figured out enough to poll the data I needed to match what the old drives report. I used the Modbus TCP book titled:
TOSVERT VF-AS1/PS1 series
Modbus TCP option unit Function Manual
MBE001Z

And converted from hex to decimal and added one to get the addresses sorted out. At some point, I may tackle what it takes to use Modbus for control, but this group of 4 drives is using hardwired control.

I still think I can only read one address at a time. I stopped the PLC long enough to download a modified PLC program to poll the most important things they want trended and didn't try to change the MSG size in elements to be more than 1 since 2 failed for every attempt I made when I was guessing at data addresses.

FD00 = HR464769 = Output Frequency
FD01 = HR464770 = Status Word
FD03 = HR464772 = Output current