Use this page for general Beckhoff terminal power-bus questions, especially mixed 5V and 24V terminal chains.
24V is the most common signal level for the terminals. However, some also support other voltage levels, for instance 5V or 12V. In that case, normally the terminal needs to be powered with the same voltage. For 5V terminals, normally an EL9505 is added before the 5V terminal in the EtherCAT chain, supplying the power bus with 5V.
Example of slaves needing 5V power supply:
If a 5V terminal is supplied with 24V it will most likely break. Make sure the terminals have the correct power supply before powering the system.
The voltage level of the power bus after (downstream of) a 5V terminal is normally also 5V. If another voltage is needed, then another system terminal is needed to set a new voltage level of the power bus.
Most scalar analog input and analog output substitutions in db/Beckhoff_3XXX
and db/Beckhoff_4XXX support override macros for common EPICS display and
conversion fields.
These macros are named with a leading underscore because the substitution file uses them as defaults for the normal record fields:
| Macro | Record field | Typical use |
|---|---|---|
_ESLO | ESLO | Scaling factor |
_EOFF | EOFF | Scaling offset |
_EGU | EGU | Engineering unit |
_PREC | PREC | Display precision |
Example:
${SCRIPTEXEC} ${ecmccfg_DIR}addSlave.cmd, "SLAVE_ID=12, HW_DESC=EL3174_0to10V, MACROS='_EGU=mm,_PREC=4'"
The same override value is applied to all scalar channels in that substitution file. If the substitution file contains different channel defaults and only one channel should change, create or use a more specific substitution file instead.
These _XXXX macros are intended for scalar analog records. They are not used
for waveform/array substitutions such as oversampling terminals.