Transmitter Hardware Security; Figure 35: Transmitter Housing Security Screws - ABB 266 MODBUS User Manual

Transmitter hardware security

Following the completion of any maintenance or service on a transmitter (rated for "Ex d" protection), the housing cover must be
re-secured. A security screw (hexagon socket screw 3 mm) and securing mechanism is built into the enclosure and housing
covers. The housing cover is designed with tabs that extend from the outline of the edge. To remove the cover, the screw must
be flush with the edge of the securing mechanism, allowing the cover to rotate.
Required tool:
— Allen wrench, 3mm, supplied with transmitter
Removing the housing cover
WARNING – Bodily injury. When the housing covers are removed and power is still connected, there is a
potential for explosion. Failure to observe this safety information may result in death or severe injury.
Do not remove housing covers in hazardous (classified) areas or explosive environments unless the area is
known to be non-hazardous. Verify an explosive atmosphere is not present before removing the housing covers
when the power is live.
1. Disconnect the power supply to the transmitter if power is not required for maintenance or troubleshooting procedures.
2. Locate the security screw (A or B) adjacent to the housing cover (Figure 35) and turn it clockwise using the provided Allen
wrench. As the screw tightens into the socket, it eliminates the obstacle from the tabs that extend from the cover. This
allows the cover to rotate past the screw.
3. Unscrew the housing cover from the transmitter.
Securing the housing cover
1. Screw the housing cover hand tight onto the transmitter.
2. Locate the security screw (A or B) in the housing (Figure 35) and turn it counterclockwise using the provided Allen wrench.
As the screw backs out from the socket, it creates an obstacle for the tabs that extend from the cover. This does not allow
the cover to rotate past the screw.
3. If power was initially removed and the unit is ready to return to service, apply power.
A

Figure 35: Transmitter housing security screws

B
266 MODBUS® multivariable transmitter User manual 2105216 Rev. AB | 45
5 Service and maintenance