# Unable to send commands to power supply using pyvisa **URL:** \ **Category:** Support\ **Created:** [12 July 2022 10:59 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582 "2022-07-12T10:59:54Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Prem206382](https://avatars.discourse-cdn.com/v4/letter/p/9de053/32.png) [@Prem206382](https://forum.core-electronics.com.au/u/Prem206382)\ **Post date:** [12 July 2022 10:59 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582/1 "2022-07-12T10:59:54Z")
Hello all, i am trying to automate the control of programmable power supply (peaktech 1565) using pyvisa. i have gone through the reference [Automating Test-Equipment with Python - Tutorial Australia](https://core-electronics.com.au/guides/automating-test-equipment-with-python/) so i used the commands based on the peaktech 1565 model manual. But I unable to send the commands. Could you check the following code and let me know , whats wrong?? ```auto import pyvisa from pyvisa import constants rm = pyvisa.ResourceManager() rm.list_resources() print("Resources detected\n{}\n".format(rm.list_resources())) psu = rm.open_resource('ASRL3::INSTR', read_termination='\r', write_termination='\r',access_mode= pyvisa.constants.AccessModes.no_lock) # Put your device IDs here # psu = rm.open_resource('ASRL3::INSTR') # psu.baud_rate = 9600 # psu.read_termination = '\r' # psu.write_termination = '\r' # psu.timeout = 2000 # values = "SOUT0" # psu.write("SOUT0") # psu.write_ascii_values('val',values) # psu.query(":SOUT0") # print(psu.session) # print(psu.visa_attributes_classes) # print(psu.get_visa_attribute(constants.VI_ATTR_RSRC_NAME)) # print('baudrate:',psu.get_visa_attribute(constants.VI_ATTR_ASRL_BAUD)) # print('parity:',psu.get_visa_attribute(constants.VI_ATTR_ASRL_PARITY)) # # print(psu.get_visa_attribute(constants.VI_ATTR_ASRL_CONNECTED)) # print('data bits:', psu.get_visa_attribute(constants.VI_ATTR_ASRL_DATA_BITS)) # print('stop bits:',psu.get_visa_attribute(constants.VI_ATTR_ASRL_STOP_BITS)) # print('flowcntrl:',psu.get_visa_attribute(constants.VI_ATTR_ASRL_FLOW_CNTRL)) # print('TMO:',psu.get_visa_attribute(constants.VI_ATTR_TMO_VALUE)) # print('TERminal enabled:',psu.get_visa_attribute(constants.VI_ATTR_TERMCHAR_EN)) # print('terminal value:',psu.get_visa_attribute(constants.VI_ATTR_TERMCHAR)) # print(psu.get_visa_attribute(constants.VI_ATTR_ASRL_ALLOW_TRANSMIT)) # print('eol:',psu.get_visa_attribute(constants.VI_ATTR_ASRL_END_IN)) # print('eol:',psu.get_visa_attribute(constants.VI_ATTR_ASRL_END_OUT)) psu.write('VOLT140') ``` ---
**Author:** ![Liam](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/liam/32/3562_2.png) [@Liam](https://forum.core-electronics.com.au/u/Liam)\ **Post date:** [14 July 2022 03:52 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582/2 "2022-07-14T03:52:02Z")
Hi Prem, Welcome to the forum!! What does your console output when running the following? ```auto import pyvisa rm = pyvisa.ResourceManager() rm.list_resources() ``` After running your code I’d also get the log using `pyvisa.log_to_screen()` at the end to see what is happening. Liam ---
**Author:** ![Prem206382](https://avatars.discourse-cdn.com/v4/letter/p/9de053/32.png) [@Prem206382](https://forum.core-electronics.com.au/u/Prem206382)\ **Post date:** [14 July 2022 10:38 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582/3 "2022-07-14T10:38:06Z")
Hi Liam, when i run those 3lines, there no output. but when i run the below code: import pyvisa rm = pyvisa.ResourceManager() rm.list\_resources() print(“Resources detected\n{}\n”.format(rm.list\_resources())) i got the console output as: Resources detected (‘ASRL3::INSTR’,) when i runned the line : pyvisa.log\_to\_screen() i got the ouput like this : 2022-07-14 16:06:48,754 - pyvisa - DEBUG - Closing ResourceManager (session: 4097) 2022-07-14 16:06:48,758 - pyvisa - DEBUG - viClose(4097,) → 0 ---
**Author:** ![Prem206382](https://avatars.discourse-cdn.com/v4/letter/p/9de053/32.png) [@Prem206382](https://forum.core-electronics.com.au/u/Prem206382)\ **Post date:** [26 July 2022 04:18 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582/4 "2022-07-26T04:18:26Z")
Hi Liam, James Any updates on this ? ---
**Author:** ![Michael](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/michael/32/3545_2.png) [@Michael](https://forum.core-electronics.com.au/u/Michael)\ **Post date:** [27 July 2022 02:00 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582/5 "2022-07-27T02:00:32Z")
@Prem206382 since we don’t stock this supply, we have no real way to verify the [command set](https://manualzz.com/doc/en/27994999/peaktech-1565-operation-manual). It looks like your device is found, since you are connecting to a serial device [ASRL](https://pyvisa.readthedocs.io/en/1.8/names.html). Are you able to query the maximum voltage allowable? (command `GMAX` from that command set). Is it possible your setpoint is being rejected because it is too high? Do you have success with `psu.write('VOLT1')` instead? How about just toggling the output with ```python # don't forget to import sleep! while True: psu.write("SOUT1") sleep(1) psu.write("SOUT0") sleep(1) ``` ---
**Author:** ![Prem206382](https://avatars.discourse-cdn.com/v4/letter/p/9de053/32.png) [@Prem206382](https://forum.core-electronics.com.au/u/Prem206382)\ **Post date:** [4 August 2022 04:42 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582/6 "2022-08-04T04:42:59Z")
@Michael Thank you so much ,. Its working now. we need to give some delay after the commands sent to Programmable supply. Like → sleep(1) or time.sleep(1) . ---
**Author:** ![Michael](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/michael/32/3545_2.png) [@Michael](https://forum.core-electronics.com.au/u/Michael)\ **Post date:** [4 August 2022 06:55 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582/7 "2022-08-04T06:55:42Z")
That’s awesome @Prem206382! So happy you found a solution 😃 Thanks for sharing it here so others can benefit from your findings 👍 ---
**Author:** ![Jegan223825](https://avatars.discourse-cdn.com/v4/letter/j/bcef8e/32.png) [@Jegan223825](https://forum.core-electronics.com.au/u/Jegan223825)\ **Post date:** [24 January 2023 08:43 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582/8 "2023-01-24T08:43:14Z")
Hi, is it possible to control PeakTech 1565 power supply using serial library in Python? ---
**Author:** ![Jeff105671](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/jeff105671/32/3729_2.png) [@Jeff105671](https://forum.core-electronics.com.au/u/Jeff105671)\ **Post date:** [24 January 2023 09:02 UTC](https://forum.core-electronics.com.au/t/unable-to-send-commands-to-power-supply-using-pyvisa/14582/9 "2023-01-24T09:02:46Z")
Any device that can communicate over a serial connection will be able to control the device. As it is supplied with a USB-to-Serial adapter you can assume that TTL levels will work for the serial interface. However, finding details might be difficult - even discovering the baud rate might require some digging.