A&D Precision Balances Communication Manual (GX-A, GF-A and GX-AE)

A&D scales and balances have always been an excellent choice when it comes to data transfer to a computer, printer or other devices. With a data format that has remained virtually unchanged throughout the company’s history, we have seen customers replace decades-old balances with new ones without having to adapt their existing data acquisition software.

This does not mean that the communication capabilities of A&D balances are not evolving. The new GX-A, GF-A and GX-AE models are particularly interesting because they are equipped with multiple interfaces and can be controlled by a connected computer (or PLC) via a large number of commands.

Communication Manual

Best of all, A&D has documented everything in a 56 page communication manual, which you can download here (PDF).

If you thought that my interface description of A&D’s FX-i and FZ-i balances was already quite comprehensive, you’ll certainly be impressed by this communication manual for the GX-A/AE and GF-A series, which covers more topics in much greater detail.

To give you an idea, you’ll find the table of contents from the communications manual below:

Introduction
1. Applicable models
2. Features of the communication function
  1. Using standard RS-232C / extension RS-232C interface
  2. Using standard USB interface
  3. Connecting multiple peripheral devices
Interface specifications
1. RS-232C
2. USB
Connecting Peripheral Devices
1. Cables needed to connect to peripheral devices
2. About data output method
3. Specific examples when connecting multiple peripheral devices at the same time
Printing Weighing Values To the Printer
1. In case of AD-8127
2. In case of AD-8126
Connecting to a PC or a PLC
1. Quick USB mode
2. Virtual COM mode
3. RS-232C
4. WinCT data transmission software (USB Virtual COM mode or RS-232C)
5. Notes when using quick USB
Data output
1. Data output mode
2. Weighing data format
3. Output examples of weighing data format
4. Other data formats
Commands
1. Control commands
2. The <AK> code and error codes
3. Command usage examples
Error codes
1. Error codes list
The UFC function
1. UFC program commands
2. Examples of creating UFC program commands
Internal settings
1. How to set
2. List of items (communication entries only)
Key lock function
1. Locking all key switches
2. Locking specified key switches
Checking the software version of the balance

Examples

One of my favorite things about this manual are the examples, which clearly presented and easy to follow:

GX-A balance: example of measuring using a container — Example of measuring using a container

Is something still missing?

In my opinion, this is the best communication manual I’ve seen from any weighing instrument manufacturer so far.

My only suggestion for improvement as far as the manual itself is concerned is to add a warning symbol next to the footnote on page 6, which mentions the 12 V voltage on pin 9. When connecting the balance to a device which also uses pin 9 in this way (such as Zebra printers), both devices could malfunction and possibly be damaged. To prevent this from happening, a custom cable must be used instead of a standard cable that connects all pins.

Tare weight and gross weight

When the tare weight is set by the operator by pressing the RE-ZERO button on the balance, it is not returned when using the “?PT” or “?T” commands. This is mentioned in the manual, but no explanation is given. It is also not possible to request the gross weight. Therefore, applications which require this data have to be designed so that the tare operation is triggered by the connected device (see example above).

Note: The UFC template language available on the GX-A/AE and GF-A balances allows the tare weight and gross weight (and of course net weight) to be sent to a connected device.

Ethernet, WiFi, Bluetooth

An Ethernet interface is optionally available, but it costs several times more than an external converter (such as Moxa’s NPort 5110A). If it was more affordable, it would attract more customers planning to connect multiple balances to a single PC for data acquisition purposes.

No wireless LAN option exists (so far). The Bluetooth adapter for the RS-232 interface is unfortunately not available in Europe. This makes it somewhat difficult to use the balances under a fume hood and transferring the weight to a computer outside.

MT-SICS

A&D could make the balances more compatible with existing systems by adding support for the MT-SICS protocol. While MT-SICS is not the holy grail of all protocols, it is widely used and supported in the weighing industry and by software developers. With companies such as Sartorius, Radwag, Kern (KCP) and Ohaus (on some models) offering support for what is effectively MT-SICS, I see no compelling reason why A&D could not do the same.

The balances already understand the “S”, “SI” and “SIR” commands also used by MT-SICS. When set to the “MT” data format, they come very close to sending the same replies as MT-SICS-compatible weighing instruments:

First line: character/byte number
Second line: A&D’s MT format (stable weight)
Third line: MT-SICS format (stable weight)
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
S						1	2	3	.	4	5		g	CR	LF
S		S						1	2	3	.	4	5		g	CR	LF

Very close, however, is sometimes not close enough (see this blog post where communication failed because of one additional “space” character).

Reading and changing settings through commands

Finally, while these balances support many commands covering a lot of functionality, it’s not possible to read and change most of the settings by using commands. If this were an option, a connected computer with a configuration software could change the balances’ settings in a quick and user-friendly way. With new technologies such as WebUSB, it may eventually be possible to change the configuration of the balance directly from a web browser.

Just before publishing this article, I took another look at A&D’s global website and noticed that they have released a program called “WinCT-ParamSet” that does exactly what I suggested above. I will take a closer look at it in a separate article. I hope that the communication manual will be updated to include the commands used by WinCT-ParamSet.

Further information on GX-A, GF-A and GX-AE precision balances

A&D global website: A&D Apollo GX-AE/A & GF-A Series
A&D Europe: A&D Apollo Series GF-A/GX-A
A&D US: A&D Apollo GX-A/GF-A Series Precision Balances
Our shop (in German): Präzisionswaage A&D GX-A

How much does DJI’s Mavic Mini drone actually weigh?

A drone with a weight of less than 250 g has significant regulatory advantages in many countries. However, there seems to be some uncertainty about the actual weight of the new DJI Mavic Mini.

I weighed mine on an A&D GX-400 precision balance, which has a readability of 0.001 g and uses an internal motorized weight to adjust (“calibrate”) itself.

With the gimbal cover removed and a battery installed, but without a micro SD card, the Mavic Mini came in at around 247.23 g:

DJI Mavic Mini weight without Micro SD card — DJI Mavic Mini weight without micro SD card by DigitalScalesBlog.com is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

The takeoff weight including a micro SD card was 247.49 g:

DJI Mavic Mini weight with Micro SD card — DJI Mavic Mini weight with micro SD card by DigitalScalesBlog.com is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Before anyone asks, I don’t have a traceable calibration certificate for this demo scale. However, I did test it using a 200 g and a 50 g class F1 weight, which gave me readings between 250.002 g and 250.004 g. I’m therefore confident that my drone has a takeoff weight of less than 248 g.

What does this mean for your Mavic Mini? Not that much, as we don’t know DJI’s manufacturing tolerances. However, I have not yet seen a credible claim that any Mavic Mini weighs more than 249 grams. Speaking of tolerances, my three batteries have the following weights:

99,15 g (used above)
99.29 g
98.75 g

The Japanese version of the drone uses lighter batteries with a lower capacity to stay below 200 g.

Note: You are welcome to use the two photos marked above under the terms of the Creative Commons Attribution-ShareAlike 4.0 International License. Please contact us regarding the acquisition of license rights if you are unable to comply with the CC terms.

Interface description (RS-232) for A&D FX-i and FZ-i precision balances

A&D’s FX-i and FZ-i precision balances are equipped with a serial interface (RS-232) and can be easily connected to a computer for data transfer (if necessary with a converter from RS-232 to USB or to Ethernet). You can, of course, also connect other devices such as a serial printer, a data logger or a secondary display.

I recently tested all communication modes and their various settings in order to update the product description in our German scales shop. Since this took me a lot of time, I also translated my findings into English for publication on this blog.

I found that all commonly used communication modes (a.k.a. transfer modes, transmission modes) are supported and that they can often be fine-tuned in a way rarely possible with other balances. Concerning the data format, the FX-i and FZ-i balances support not only A&D’s standard format, but also several other formats which might make these scales suitable as a drop-in replacement for older Mettler Toledo or Sartorius balances. However, the more recent SICS protocol was not implemented.

The balances support a number of commands for bidirectional communication. However, not all applications and settings are accessible via remote commands (for example, the limits for checkweighing cannot be set by a connected computer).

You can use any terminal software to test communication via the RS-232 interface (e.g. HTerm or PuTTY). For productive use, I recommend A&D’s free WinCT software or our Simple Data Logger software. The best integration can often be achieved by customizing your own software to communicate directly with the balance.

RS-232 interface and cable

FX-i and FZ-i balances have a built-in DE9M connector and require a straight (1:1) cable (not a null modem cable):

Interface parameters

Default settings are highlighted in bold:

Baud rate: 600, 1200, 2400, 4800, 9600, 19200
Data bits: 7 bits or 8 bits
Parity: even, odd (for 7 data bits), none (for 8 data bits)
Stop bits: 1 bit
Data flow control (handshaking): none (RTS and CTS lines are connected internally but not used for actual flow control).

Data format

By default, the balances use the proven A&D format and transmit 17 ASCII characters for each weight value:

First line: number; second line: ASCII characters sent by the balance; third line: hexadecimal value
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17
S	T	,	+	0	0	4	5	6	.	8	9			g	CR	LF
53	54	2C	2B	30	30	34	35	36	2E	38	39	20	20	67	0D	0A

As far as I know, the very first scale from A&D with a data interface already used the same format. This is very impressive, particularly when other manufacturers sometimes change the data format between firmware updates or even between transmission modes.

As alternatives to the A&D format, 5 further data formats can be used. The user manual (PDF) contains a detailed description in chapter 10-6.

Communication modes

The corresponding setting in the menu of the balance is indicated in [square brackets].

Key mode: The weight is transmitted when the PRINT button on the balance is pressed.
- Mode A: Only when the weight is stable [dout / Prt 0].
- Mode B: Immediate transmission (stable and unstable weight) [dout / Prt 4].
- Mode C: The balance waits until the weight has stabilized and then transmits it [dout / Prt 5].
Auto-print: The weight is automatically transmitted after stabilization.
- Mode A: Return to zero is required before next transmission [dout / Prt 1]. You can set which range around zero counts as “zero” (10, 100 or 1000 digits) [dout / AP-b]. You can also specify whether only positive, negative or all values should be transmitted [dout /AP-P].
- Mode B: No return to zero is required before the next transmission [dout / Prt 2]. You can set the required difference from the last stable value (10, 100 or 1000 digits) [dout / AP-b]. You can also specify whether lower, higher or all values should be transmitted (compared to the last stable value) [dout /AP-P].
Stream mode: Continuous transmission of 5, 10 or 20 values/s [dout / Prt 3]. The frequency is determined by the display refresh rate [bASFnc / SPd]. This mode is not suitable if you connected a printer or hardware data logger to the balance, but it is required if you want to use an external display. Our data logger software can also easily handle this number of values per second.
Interval mode: Transmission of a value every 2, 5, 10, 30 or 60 seconds or every 2, 5, or 10 minutes [dout / Prt 6].
Command mode: The balance responds to commands received over the interface (bi-directional communication). Available in all modes, see commands below.

In mode 1, 2 and 4, the display blinks to signal that the weight has been transmitted.

Supported commands

“Q” is used to request the displayed weight immediately, while “S” is used to request the weight once it has stabilized. All commands must be terminated with carriage return and line feed:

No.:	1	2	3
ASCII:	Q	CR	LF
Hex:	51	OD	0A

Complete list of commands (in alphabetical order):

?ID	Requests the balance ID (can be set through the menu).
?PT	Requests the tare value set by using the PT or T command (does not work for tare values set by using the RE-ZERO button on the scale)
?SN	Requests the balance’s serial number.
?TN	Request the balance’s model name.
C	Cancels the S or SIR command (before completion).
CAL	Same as pressing the CAL button.
<ESC>P	Same as the “S” command. <ESC> is the escape control character (1Bh).
<ESC>T	Same as pressing the RE-ZERO button.
EXC	Calibration using an external weight (only for FZ-i).
Q	Requests the weight data immediately.
OFF	Turns the balance off.
ON	Turns the balance on.
P	Same as the ON:OFF button (“P” = power?).
PRT	Same as pressing the PRINT key.
PT	Sets a tare value, PT:xxx.x g. The unit must be transmitted using A&D’s format (3 characters, right-justified, padded with spaces).
R	Same as pressing the RE-ZERO key.
S	Request the stabilized weight. If the weight is currently not stable, the balance waits until it has stabilized. There seems to be no timeout (though the command can be cancelled with “C”).
SI	Same as “Q”.
SIR	Switch to stream mode (continuous transmission).
SMP	Same as pressing the SAMPLE key
T	Tares the balance.
U	Same as pressing the MODE key.
Z	Same as pressing the RE-ZERO key.

Other settings affecting RS-232 data transmission

You can set the balance to acknowledge valid commands with the ACK control character (06h) and to reply to invalid with “EC” and an error number [SiF / ErCd]. The manual contains detailed information and examples in chapter 16-2.

The terminator can be changed from carriage return and line feed (0Dh 0Ah) to carriage return (0Dh) [SiF / CrLf]. This affects both the output and the input (commands).

It’s also possible to change the decimal point to a comma [bASFnc / Pnt].

The balance can re-zero (tare) itself after sending the weight, which is useful during formulation [dout / Ar-d].

FZ-i balances are equipped with an internal clock and calendar and can output the time, date or time and date [bASFnc / dout / S-td]. ~~According to the manual, this only works when outputting GLP data and not with individual weight values (I will test this later this week).~~ This information can be added to the weight data [dout / S-td].

You can use the animal weighing application to calculate an average weight and automatically output it (as shown in this short video). Statistical calculation mode can output numbered individual weight values and summarized statistical data.

You’ll find further settings in a function table in the user manual (chapter 10).