# Issues accessing /dev/ttySer0 on Epic **URL:** \ **Category:** Ignition\ **Created:** [April 16, 2025, 4:38pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185 "2025-04-16T16:38:40Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![Thomas\_Salisbury](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/thomas_salisbury/32/62046_2.png) [@Thomas\_Salisbury](https://forum.inductiveautomation.com/u/Thomas_Salisbury)\ **Post date:** [April 16, 2025, 4:38pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/1 "2025-04-16T16:38:40Z")
I seem to be having an issue accessing "/dev/ttySer0" as the Epic says it is located. We can get it fine in NodeRed, but are trying to script it in Ignition. Does anyone have ideas where i might be off? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [April 16, 2025, 4:40pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/2 "2025-04-16T16:40:04Z")
Do you have the Ignition serial module? What you have tried so far? ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [April 16, 2025, 4:41pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/3 "2025-04-16T16:41:48Z")
That's an unusual device name. Are you sure it isn't `/dev/ttyS0` ? ---
**Author:** ![Thomas\_Salisbury](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/thomas_salisbury/32/62046_2.png) [@Thomas\_Salisbury](https://forum.inductiveautomation.com/u/Thomas_Salisbury)\ **Post date:** [April 16, 2025, 4:42pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/4 "2025-04-16T16:42:45Z")
We are running Edge license which shows to have access to the serial functions. currently I am trying a basic in the script window ```python system.serial.configureSerialPort(port="/dev/ttySer0", bitRate=system.serial.BIT_RATE_9600, dataBits=system.serial.DATA_BITS_8, handshake=system.serial.HANDSHAKE_NONE, hardwareFlowControl=False, parity=system.serial.PARITY_NONE, stopBits=system.serial.STOP_BITS_2) system.serial.openSerialPort("/dev/ttySer0") ``` ---
**Author:** ![Thomas\_Salisbury](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/thomas_salisbury/32/62046_2.png) [@Thomas\_Salisbury](https://forum.inductiveautomation.com/u/Thomas_Salisbury)\ **Post date:** [April 16, 2025, 4:43pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/5 "2025-04-16T16:43:55Z")
Epis its as ![image](https://us1.discourse-cdn.com/inductiveautomation/original/3X/f/3/f3d54b3a1437f81e62213aaa03e184a1e31f2376.png) ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [April 16, 2025, 4:44pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/6 "2025-04-16T16:44:10Z")
> [@Thomas\_Salisbury](#): > > currently I am trying a basic in the script window and? ---
**Author:** ![Thomas\_Salisbury](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/thomas_salisbury/32/62046_2.png) [@Thomas\_Salisbury](https://forum.inductiveautomation.com/u/Thomas_Salisbury)\ **Post date:** [April 16, 2025, 4:44pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/7 "2025-04-16T16:44:47Z")
"Traceback (most recent call last): File "", line 2, in at com.inductiveautomation.ignition.modules.serial.scripting.SerialScriptModule.openSerialPort(SerialScriptModule.java:258) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) at java.base/java.lang.reflect.Method.invoke(Unknown Source) java.io.IOException: java.io.IOException: failed to open port: /dev/ttySer0 " ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [April 16, 2025, 4:44pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/8 "2025-04-16T16:44:51Z")
OK. > [@Thomas\_Salisbury](#): > > in the script window Those functions will run in the designer, not in the gateway, if you are using the designer's script console. Use an actual gateway event to test. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [April 16, 2025, 4:45pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/9 "2025-04-16T16:45:34Z")
Right, what Phil is saying is true: you need to execute the script in a scope that actually runs on the Gateway, since you can't be running your Designer on the device itself. ---
**Author:** ![Thomas\_Salisbury](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/thomas_salisbury/32/62046_2.png) [@Thomas\_Salisbury](https://forum.inductiveautomation.com/u/Thomas_Salisbury)\ **Post date:** [April 16, 2025, 4:50pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/10 "2025-04-16T16:50:09Z")
Yes, i started on a gateway script. It was the same issue. I am thinking now that Opto Epic only allows access to the two USB ports to very select things running on the epic, and Ignition may not be one of them. I move the comms to the serial device on the back plane. testing that now ---
**Author:** ![Thomas\_Salisbury](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/thomas_salisbury/32/62046_2.png) [@Thomas\_Salisbury](https://forum.inductiveautomation.com/u/Thomas_Salisbury)\ **Post date:** [April 16, 2025, 4:54pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/11 "2025-04-16T16:54:24Z")
oh,i get what you are saying. I will try that ---
**Author:** ![Thomas\_Salisbury](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/thomas_salisbury/32/62046_2.png) [@Thomas\_Salisbury](https://forum.inductiveautomation.com/u/Thomas_Salisbury)\ **Post date:** [April 16, 2025, 4:57pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/12 "2025-04-16T16:57:58Z")
Same issue > Caused by: org.python.core.PyException: java.io.IOException: java.io.IOException: failed to open port: /dev/ttySerSys64 ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [April 16, 2025, 4:59pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/13 "2025-04-16T16:59:50Z")
Is the user running the Ignition service a member of the dialout group? That is generally the owner of those device nodes. You may want to shell into the Epic and examine the ownership and the Ignition service permissions. ---
**Author:** ![Thomas\_Salisbury](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/thomas_salisbury/32/62046_2.png) [@Thomas\_Salisbury](https://forum.inductiveautomation.com/u/Thomas_Salisbury)\ **Post date:** [April 16, 2025, 6:39pm UTC](https://forum.inductiveautomation.com/t/issues-accessing-dev-ttyser0-on-epic/105185/14 "2025-04-16T18:39:10Z")
I've got Opto looking into it. Seems like there is an issue. See what they say