1747-L20E

The 1747-L20E SLC 500 Fixed Controller by Allen-Bradley is a fixed controller with a power supply, a processor, and 20 I/O points all wrapped up in one compact design. It has a power supply rating of 120-240V AC and comes with an 8kHz high-speed counter. The 1747-L20E has 12 current sinking inputs, 24V DC inputs, and 8 transistor-based outputs. It has a maximum of 50VA of power across its circuit, it offers 200mA of the 24V DC of the user’s power, and 1.25A fuse protection at 120-240V AC. It allows communication via the receive-only (slave) DH-485 communication port and the display controller’s mode (status) through the LED light indicators. It has a 1K program memory and a 5-year lithium battery-backed RAM and an optional UVPROM or EEPROM backup.

The 1747-L20E processor scan programs at a rate of 8ms per 1K instructions, and the maximum hold-up time range between scans (load dependent) is from20-700ms. It has 24 and 14 AWG for its standard wire size, and it provides a NEMA Standard ICS 2-230 rated noise immunity and is UL and CSA-certified. The 1747-L20E has an operational temperature and relative humidity range of 0-60 degrees Celsius at 5-95% without condensation and it is stored at a non-operating temperature range of -40-85 degrees Celsius. During installation, make sure you properly ground the 1747-L20E and all the devices connected to it. Please note that fixed I/O processors like the 1747-L20E use transistor outputs and are prone to produce transient pulses. This is caused by a minimum load being connected to the output. It can also manifest itself when the external DC supply voltage is fed to the common output terminal. To avoid this, upi can raise the on-state load current by installing an extra resistor parallel to the load.