ETommens eTM-xxxxP Series

eTommens eTM-xxxxP

Status	in progress
Source code	etommens-etm-xxxxp
Channels	1
Voltage/current (CH1)	various
Connectivity	USB/serial, RS232
Features	programmable presets, over voltage protection, over current protection, output on/off
Website	etommens.com

The eTommens eTM-xxxxP series are 1 channel switch-mode programmable DC power supplies with both USB/serial and RS232 connectivity.

The devices are also sold as rebranded versions by e.g. Hanmatek and Rockseed.

Devices

Device	OEM/Rebranded	Voltage range	Current range	Power	Resolution	Port Class, Model
eTommens eTM305P	Hanmatek HM305P, Rockseed RS305P	0-30 V	0-5 A	150 W	10mv	0x4B50, 305
eTommens eTM3010P	Hanmatek HM310P, RockSeed RS310P	0-30 V	0-10 A	300 W	10mv	0x4B50, 3010
eTommens eTM1003P	—	0-100 V	0-3 A	300 W	10mv	—
eTommens eTM1520P	—	0-15 V	0-20 A	300 W	10mv	—
eTommens eTM605P	Rockseed RS605P	0-60 V	0-5 A	300 W	10mv	—
eTommens eTM1502P	—	0-150 V	0-2 A	300 W	10mv	—

Note: libsigrok support for these devices is pending the merge of this PR - https://github.com/sigrokproject/libsigrok/pull/100

Note: The libsigrok driver needs to know about the device's class and model, retrievable with hm305.py please let us know.

Protocol

Modbus RTU only function codes 0x03 and 0x06 are supported (according to the pdf that came with the device).(Wikipedia). Baudrate defaults to 9600, 1 start bit, 8 data bits, no checkbits and 1 stop bit. Registers are 16bits, bigendian.

Name	Register Address	Access
Output State	0x0001	RW
Protection State	0x0002	R
Model ID	0x0004	R
Output Voltage	0x0010	R
Output Current	0x0011	R
Output Power high bits	0x0012	R
Output Power low bits	0x0013	R
Voltage Target	0x0030	RW
Current Limit	0x0031	RW
OVP Value	0x0020	RW
OCP Value	0x0021	RW
OPP Value high bits	0x0022	RW
OPP Value low bits	0x0023	RW
Decimals	0x0005	R

1. There is actually no OPP button on the power supply, but the protocol documentation lists, the address for it. Not relevant at the moment for a driver, since sigrok seems to have no OPP support anyway. 2. In the protocol documentation there is no mention of how to set the presets M1 to M6. But it seems they start at address 0x1000. This needs to be researched still, but I currently do not know how to handle presets in sigrok, so I need to find that out too. Also there is some other addresses listed in config files that are with the software provided, these need to be researched too.

3. The Protection State registers contains looks as follow and the designated bit goes high if the protection state is active:

Bit	Designation	Description
0	OVP	Over Voltage Protection
1	OCP	Over Current Protection
2	OPP	Over Power Protection
3	OTP	Over Temperature Protection
4	SCP	Short Circuit Protection
5
6
7
8

the 2nd byte does not give any information, and seems to always be 0.

4. The decimals registers contains the the decimal information for Voltage, Current and Power. The lower 12 bits are used with 4bits for each value. If the register content is 0x0321, it means Voltage has 3 decimals, Current 2 and Power 1.

Researched Registers:

Name	Register Address	Access	Notes
Voltage upper Limit (UH)	0xC11E	R	4 bytes long, contains high voltage limit (like the limit you get when turning the knob on the device), did not even try to write to it, values are same as current in format so divide int value by 10^digits
Current upper Limit (IH)	0xC12E	R	4 bytes long, contains high current limit (like the limit you get when turning the knob on the device), did not even try to write to it, values are same as current in format so divide int value by 10^digits
Voltage lower Limit? (UL)	0xC110	R	4 bytes long, not sure what this is, it contains the value 10. But my supply outputs at 1 already.
Current lower Limit? (IL)	0xC120	R	4 bytes long, not sure what this is, it contains the value 21. And my power supply actually only starts outputting when set to 21mA or above.
Buzzer	0x8804	RW	2 bytes long, you can enable (write 0x0001) or disable (write 0x0000) the buzzer. It beeps on every single click (and on startup ) so probably no one wants to enable this ever.
defaultshow	0x8802	?	2 bytes long, no idea what it is about
powerstat	0x8801	?	2 bytes long, no idea what it is about
scp	0x8803	R	2 bytes long, no idea what it is about, i can't write to it, maybe my model just has no scp support?
sdtime	0xCCCC	?	2 bytes long, no idea what it is about
settimespan	0x0032	?	2 bytes long, timespan till it auto disables output, but only if you use the preset list function. Don't see how this is useful for anything since the value only matters per preset.
preset voltage	0x1000+(0 to 5)*10	RW	2 bytes long, registers for presets M1 to M6
preset current	0x1001+(0 to 5)*10	RW	2 bytes long, registers for presets M1 to M6
preset timespan	0x1002+(0 to 5)*10	RW	2 bytes long, registers for presets M1 to M6, max value 9999 (this is seconds, so max is about 2,78h)
preset enabled (included in list)	0x1003+(0 to 5)*10	RW	2 bytes long, registers for presets M1 to M6

Resources

• EEVblog forum thread
• GitHub - Python control script
• GitHub - Electron based application, offers Charts and CSV Export