Emerson P/N 400361-00 Writing to the User Bit Register, Configuring the User Bit Mask Register

than having to access them individually. In the SM-EZMotion module it is possible to access 32 User Bits in a single parameter. This parameter is named BitRegister.#.Value. Because some of the 32 User Bits may be used by the program, and should not be modified from the network communications, it is possible to "Mask Off" certain bits. Masking bits prevents them from being modified in the program when the 32-bit parameter is written to.

When a User Bit Register (group of 32 User Bits) is written to, the value is then logic-AND'ed with the mask to determine the resulting state of each of the 32 individual bits. If the individual bit value of the 32-bit mask is "1", then the corresponding bit from the written 32-bit parameter is passed through, and the resulting value stored in the specific bit will be the written bit value. If the bit value of the 32-bit mask is "0", then that particular bit is blocked (or masked), and the resulting bit value does not change, (Original Value AND NOT 32-Bit Mask) or (Value Written over Network AND 32-Bit Mask). An example of this is shown in Figure 84.

Original	Bit #31																15															0
	1	0	0	0	0	0	0	1	0	1	0	0	0	0	0	0	1	0	0	0	0	0	1	0	0	0	0	0	0	0	0	0
Value
Value written	0	1	1	0	1	0	0	0	0	1	1	1	1	0	0	0	0	1	1	1	1	1	1	1	0	1	0	1	0	1	1	0
over network
32-bit Mask	0	1	0	1	0	1	0	1	0	1	0	1	0	1	0	1	0	1	0	1	0	1	0	1	0	1	0	1	0	1	0	1
Result stored	1	1	0	0	0	0	0	0	0	1	0	1	0	0	0	0	1	1	0	1	0	1	1	1	0	1	0	1	0	1	0	0
in each bit

Figure 84: Writing to the User Bit Register

The Mask is only used when WRITING to the 32-bit parameter, BitRegister.#.Value. When reading the 32-bit value, all bits are read regardless of the mask.

			FM-3/4
	Write
Network
Master	Read			AND
		Mask

Value

Written data is AND’ed with the Mask and then written into 32-bit Value.

Read data is read directly from the 32-bit Value and bypasses the Mask.

Figure 85: User Bit Read/Write Process

Configuring the User Bit Mask Register

The User Bit Mask is a 32-bit parameter that can be configured through Power Tools Pro, in the User Program, or over the communications network. The default value for the Mask register is 0xFFFFFFFF (HEX), or all bits ON. To change the Mask value using PowerTools Pro, navigate to the Mask tab on the User Bits view, see Figure 86.

Figure 86: User Bits View (Mask Tab)

In the User Bits view - Mask Tab, each bit of the Mask can be set to 0 or 1 individually. ON (or 1) is indicated by a shaded square, and OFF (or 0) is indicated by an empty square. Bit 31 is the most significant bit in the word, and bit 0 is the least significant bit. If the bit is shaded, it means

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