Chaneg voltage on EL5042

hugo/content/manual/knowledgebase/hardware/EL5042.md

@@ -43,9 +43,32 @@ Make sure the encoder is powered with the correct voltage. Most encoders require
 **Never apply a higher voltage than the specified operating voltage for the encoder.**
 {{% /notice %}}
 
-The EL5042 can supply 5V or 9V. The default setting is 5V and in order to change the setting to 9V a special sequence need to be executed (see EL5042 manual).
+The EL5042 can supply 5V or 9V. The default setting is 5V and in order to change the setting to 9V a special sequence need to be executed (see below and the EL5042 manual).
 
-After ensuring that the encoder is correctly supplied, the verify the power consumption of the encoder and compare with the specified consumption. If the power consumption does not match, the encoder might be broken or a faulty cabling.
+{{% notice warning %}}
+**The voltage cannot be different on the two channels. A change to 9V will apply to both channels!**
+{{% /notice %}}
+
+From EL5042 manual:
+```
+#     Setting the encoder supply voltage
+#        Condition: To write 0x8008:12 “Supply Voltage”, the value 0x72657375 (ASCII: “user”) must be set in 0xF008 “Code word”.
+#
+#        Set the value into index 0x8008:12 “Supply Voltage” (Specification in steps of 0.1 V).
+#        Only the values 50 (5.0 V) and 90 (9.0 V) are permissible.
+#        This setting applies to both channels.
+#        Before switching to 9.0 V make sure that both BiSS encoders support the extended voltage range!
+#
+#        The encoder supply voltage is set for both channels in object 0x8008:12
+#  --------------------------------------------------------------------------------------------------------------------------
+```
+After the above sequence is executed, the slave must go to INIT state before the new settings is applied. This can be done with the ethercat tool:
+```
+ethercat states -m<master_id> -p<slave_id> INIT
+# then back to preop
+ethercat rescan
+```
+After ensuring that the encoder is correctly supplied, then verify the power consumption of the encoder and compare with the specified consumption. If the power consumption does not match, the encoder might be broken or a faulty cabling.
 
 #### Long cable lengths