11 U02124ML-01-UK
4.7 INPUT SIGNAL INVERSION
Solder switches SWI and SW2 and the main PCB assembly (U0092) allow
the input data logic polarity to be inverted. It is applicable both for external
powered and 6155AS powered 2/20mA current loops
i.e. 2/20mA = LOGIC 1 = SPACE
0mA = LOGIC 0 = MARK
Follow the procedure below to select this feature if required.
PROCEDURE.
The procedure for all other aspects of configuration remain unchanged.
1. Remove any connector(s) from the rear of the 6155AS
2. Remove the front panel lens
3. Remove the two size #8 case retaining screws from the rear of the
6155AS
4. The 6155AS meter can now slide forward out of its casing
5. Open-circuit solder-switch positions SWI-A and SW2-A
6. Short-circuit solder-switch positions SWI-B and SW2-B
7. Re-assemble the 6155AS meter now by reversing steps 1 to 4. above
Figure 1 Location of solder switches SW1 and SW2
Note.
The above configuration is only normally used for current loop operation. For
operation with other standard inputs (TTL, RS232, RS422, RS423 or
RS485) the solder switches SW1 and SW2 should be returned to the normal
configuration.
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