10
2.4.2 20mA Current Loop Interface
To in stall the 20mA cur rent loop in ter face, dis con nect pow er to the print er and fol low the pro ce dure for
re mov ing the cov ers as described in Section 2.4.1. Once the covers are re moved, continue with the following
steps:
1. If you are replacing the 20mA current loop chips, carefully remove chips from sockets U5 and U6
with a chip removal tool.
2. Install the new 20mA current loop chips. The 4100 chip goes in socket U5; the 4200 chip goes in
socket U6 (see Figure 2-10). The notch on the top of each chip must face the back of the printer when
installed.
3. Replace covers using the procedure described in Section 2.4.7.
2.4.3 RS-422A
Interface
To install the RS-422A interface, disconnect power to the printer and follow the procedure for removing the
covers as described in Section 2.4.1. Once the covers are removed, continue with the following steps:
1. If you are replacing the RS-422A chip, carefully remove chip from socket U8 with a chip removal
tool.
2. Install the new RS-422A chip in socket U8 (see Figure 2-10). The notch on the top of the chip must
face the back of the printer when installed.
3. Replace covers using the procedure described in Section 2.4.7.
2.4.4 Parallel
Interface
To install the parallel interface, disconnect power to the printer and follow the procedure for removing the
covers as described in Section 2.4.1. Once the covers are removed, continue with the following steps:
1. Remove the cover plate from the parallel input port.
2. Plug the parallel interface ribbon cable into socket J1 (see Figure 2-10).
3. Attach the connector to the parallel input port using the screws, lock washers, and nuts provided.
4. Set DIP switch 2-8 on for parallel communications.
5. Replace covers using the procedure described in Section 2.4.7.
2.4.5 Switch
Module
To install the switch module, disconnect power to the printer and follow the procedure for removing the cov-
ers and print mechanism as described in Section 2.4.1. Once the print mechanism is removed, continue with
the fol low ing steps:
1. Turn the printer on its side and remove the two screws shown in Figure 2-11. (These screws are used,
in the same locations, to attach the switch module.) Remove the blank plate assembly from the base
enclosure.
2. Install the switch module assembly in the same location, aligning the holes in the assembly with those
in the base enclosure. Reinstall screws removed in Step 1.
3. Plug the switch module cable onto connector J8 (see Figure 2-10).
4. Replace print mechanism and covers using the procedure described in Section 2.4.7.
5. Use the printer self-test procedure described in Section 2.3 to verify installation of the option.
