Pin assignment, display and diagnosis

EL3218

EL3218 – pin assignment

Terminal points 1 – 16 (left side)			Terminal points 1' – 16' (right side)
Terminal point	No.	Comment	Terminal point	No.	Comment
+R1	1	Input +R1, current-carrying	+R5	1‘	Input -R5, current-carrying
RL1	2	Input RL1, de-energized sense line	RL5	2‘	Input RL5, de-energized sense line
+R2	3	Input +R2, current-carrying	+R6	3‘	Input +R6, current-carrying
RL2	4	Input RL2, de-energized sense line	RL6	4‘	Input RL6, de-energized sense line
+R3	5	Input +R3, current-carrying	+R7	5‘	Input +R7, current-carrying
RL3	6	Input RL3, de-energized sense line	RL7	6‘	Input RL7, de-energized sense line
+R4	7	Input +R4, current-carrying	+R8	7‘	Input +R8, current-carrying
RL4	8	Input RL4, de-energized sense line	RL8	8‘	Input RL8, de-energized sense line
-R1	9	Input -R1, current-carrying	-R5	9‘	Input -R5, current-carrying
n. c.	10	not used	n. c.	10‘	not used
-R2	11	Input -R2, current-carrying	-R6	11‘	Input -R6, current-carrying
n. c.	12	not used	n. c.	12‘	not used
-R3	13	Input -R3, current-carrying	-R7	13‘	Input -R7, current-carrying
n. c.	14	not used	n. c.	14‘	not used
-R4	15	Input -R4, current-carrying	-R8	15‘	Input -R8, current-carrying
n. c.	16	not used	n. c.	16‘	not used

Notice

Increased measurement uncertainty with signal bundling of the AGND line

In this terminal, the AGND contacts (signal return line -R) are connected in the terminal.
If the connection lines are to be reduced on the system side, one line instead of n lines can be used for all n RTD sensors at this terminal.
However, since each channel individually permanently drives its measuring current (some 100 µA, see explanations chapter "RTD measurement in EL32xx"), all n RTD currents then flow via one line, there is an n-fold increase in voltage drop there, which is also recorded by the ratiometric voltage measurement in the terminal.
The result is the same as for long lines. If RTD sensors are to be connected in this way, a system-side check and, if necessary, compensation using WireCalibration CoE 0x80n0:1B (convert voltage drop to apparent line resistance for this purpose) or UserScale 0x80n0:11/12 is recommended.
Since the line resistances are temperature-dependent and the measuring current depends on the RTD resistance, however, such a static "compensation" cannot achieve the measurement uncertainty as in operation with two lines connected short.

	Connection of analog RTD signal lines To ensure that the analog signals can be measured with as little interference as possible, also observe the notes in the chapter "Connection of analog RTD signal lines".

EL3218 – LEDs

LED	Color	Meaning
RUN	green	This LED indicates the terminal's operating state:
		off	State of the EtherCAT State Machine: INIT = initialization of the terminal or BOOTSTRAP = function for terminal firmware updates
		flashing	State of the EtherCAT State Machine: PREOP = function for mailbox communication and different default settings set
		single flash	State of the EtherCAT State Machine: SAFEOP = verification of the Sync Manager channels and the distributed clocks. Outputs remain in safe state
		on	State of the EtherCAT State Machine: OP = normal operating state; mailbox and process data communication is possible
ERROR1 - 8	red	Short circuit or wire break. The resistance value is in the invalid range of the characteristic curve.