Multiranger-200 is not responding for the modbus command

I've never read data from an ultrasonic box before, but some Modbus conventions apply nonetheless.

1) be careful of decimal to hex conversions,. your hex and decimal values are not equivalent:

AF7Dhex = 44925 decimal
B74D hex = 46925 decimal

2) Your problem, in part, is starting with the wrong decimal value for the register.

The leading numeral 4 is not used in a Modbus packet message. 4xxxx defines a holding register. But the 4 is not used, only the xxxx is used.

A 03 function/command to read holding register 46925 would use the hex equivalent for 6925, not 46925.

3) You appear to be trying to read parameter 925, correct?
46925 is a format register. 44925 is a parameter register. (see page 112 pdf, Parameter Access. in the Multi 200 manual)

4925 decimal is 133D hex

It isn't clear at first reading of the manual whether any register's value can just be read with an 03 command, without writing formatting data first, but if it were me, I'd try reading 133D hex (4925 decimal) and see if there isn't a response.

1) Yes, we all live with errors and typos . . .

2) The absence of a Modbus error response is suspicious.

I just noticed that your Modbus comm settings in the 72x parameters are all index 2. Why?

I have to admit that I'm not clear on where indexed settings take effect, where they don't.

Obviously a relay 1 is index 1, relay 2 is index 2, relay 3 is index 3, but how does indexing affect Modbus comm settings? There's only one comm port.

I wonder whether index 2 Modbus comm settings are, shall we say, fictional? Are your master polls ignored because index 1 is not set to Modbus?

I would consider making sure the comm settings for index 1 are like your index 2 settings, unless you've discovered an explanation that establishes that index 2 is what you need.

3) There's the phenomenon of one offset, where Modbus registers start at 0001, but register 0001's address is 0000. Some vendors swap the names 'register' and 'address' or only state one of them.

Hence, it isn't clear whether the Modbus register values cited by Siemens in its documentation are registers or addresses, but it's always possible to be off by one.

In the case of 4925 decimal, (133D hex), I'd recommend trying 133C and 133E to see if expected data shows up one count off.

I use the RJ-11 port for RS-232 with a Dolphin cable for Dolphin software or PDM connection and I've never actually used a Multi's RS-485 port for Modbus or software comm.

Thanks for the explanation of the indexing for comm ports; there is more than one (232 and 485) port, hence the index. Your explanation triggered something else - you've got no Modbus response and the comm port is RS-485.

Have you gotten any confirmation of good comm over RS-485? It could be the data lines are backwards.

Two wire, half duplex RS-485 has one major issue that can prevent successful comm.

There is no enforced standard for the designation or labeling of the data lines. The data lines are sometimes called A/B (that's what MultiRanger terminals are labeled) or (+)/(-), Tx+/Tx-, Tx/Rx-, DO/DO(not). Different divisions within a company can sell products with different labeling.

Although A on the Modbus master is supposed to connect to A on the slave, sometimes the functionality is reversed and A connects to B. That's just the way it is.

Connecting RS-485 data lines backwards will not damage the comm line drivers, but comm will not work until the correct connections are achieved. The classic work-around when RS-485 does not 'connect' is to swap the data lines and try again.

The absence of unexpected Modbus data or a Modbus error reponse probably means that the physical 485 connection isn't established. Try the data line swap.

If a Data line swap on the 485 port fails, try the RS-232 port.

Ironic, I got my hands on a single channel Multi100 and just connected to it via Modscan32

I used a known good RS-232 cable, connected to the RJ-12 connection the MultiRanger.

Configured index 01 for Modbus parameters at P770 and up, as shown on pg 91 of the manual (Changed index to 01, then used the Modbus values as shown for 770 and up, with the exception of a 19.2K baud rate).

I connected with a Modbus master test program, Modscan 32 on PC COM port 1.
Modscan saw the MultiRanger 100 at Modbus slave address 1

To check comm, I polled address 0064 for the model ID and a value 6 was returned, 6 representing a MultiRanger 100, which is correct (see manual pdf pg 107).

All values that I refer to are integer values.

I connected using Banner Engineering's MQDC-401 USB/RS-485 cable with
Banner A- (pin 4, black) connected to MultiRanger terminal 35, A
Banner B+ (pin 2, white) connected to MultiRanger terminal 36, B

I checked Windows Device Manager > COM ports to find which COM port the USB/RS-485 adapter installed itself on. On my PC it was COM 6.

I connected Modscan32 from PC COM 6
Modscan32 again showed a value 6 at register 0064.

I did not disable the RS-232 port when I did this. On this MultiRanger, both RS-232 and RS-485 ports were configured for Modbus RTU (Parameter 770 = 3 for both index 01 and 02). Only one port can be used at any given time, but both ports can be configured for Modbus.

On page 109, Point Data (R41,101 - R41,031) it provides register info for common data.
Register 41010 is the P920 reading.

Modscan sees the P920 reading at 1010 as 2510 ±1 when the front panel display shows 30.12 inches distance with 8.02mA output.

To interpret 2510, page 109 pdf says the reading is interpreted as a percentage of full scale, multiplied by 100 and gives a table of examples:
Reading Value
0 0.00%
5000 50.00%
7564 75.64%
20,000200.00%

In this case, the display reading of 30.12 (inches) = 30.12/120 = 25.1% = Modbus register 1010 = 2510, where 2510/100 = 25.1%

Modscan shows the 2 reference data registers reading 30015 for each of the two registers. I am clueless as to what that means.

register 1110 = mA output (0-20,000): actual 11.26mA, Modbus = 1127 (inferred two decimal places).

41011 and 41012 should have display value for a 2nd channel (transducer) and a difference value if the MultiRanger is configured for that.

Summary, checkModbus by proving you can read readily accessible data
Try
0064 for a model number code
1010 for channel 1 value in percent of span * 100
1011 for channel 2
1110 for mA output * 100