Omron NT31 NT31C manual Maintenance of the NT31/NT31C, Spare PT, Backlight

	Maintenance of the NT31/NT31C				Section 7-3
	Error Details		Displayed Probable Cause		Remedy
	Time-out Error		The connecting cables are not		Check the communication cable connection and
			connected correctly. (Send/Receive)		perform a conductivity test. If there is a fault,
					replace the cable. For details on communication
					cables, refer to Section 4 Connecting to the Host
					from the RS-232C Port, and Section 5 Connecting
					to the Host from the RS-422A/485 Port.
			The communication service of the		Check that the host is capable of communicating
			host is stopped. (Send/Receive)		with the NT31/NT31C (confirm that the
					communication settings of the host and
					NT31/NT31C match).
			Time-out Interval is too short. (Send)		Set a longer value for Time-out Interval at the host
					side.
			Time-out Interval is too short.		Set a longer value for Time-out Interval in the
			(Receive)		System Menu. (6-9-12 Setting the Time-out Interval,
					page 185) It may also be possible to solve the
					problem by shortening the host cycle time.
	PC Unit No. Error		The unit # does not match that set		Re-set the unit number at the host side to 0.
			on the PC.
			Noise caused data corruption during		Carry out grounding work in accordance with the
			communication.		conditions by referring to 3-1-4 Grounding, page 34.
	NAK received		——		Check the settings for allocated words and bits.
					If noise is a possible factor, distance the cable from
					sources of noise and insert a noise filter in the
					power supply line.
					If using the equipment in a location subject to a lot
					of noise, use a cable with a high degree of
					protection against noise for the transmission route.
					Also make the cable as short as possible.
	Undefined Command		The host is not supported.		Check the PC model used for the host.
	Error
			Instruction level 3 is not effective.		Check that the instruction level setting for the host is
					level 1, 2, 3.
	Data Over Flow Error		Communication command from the		Set flow control method in the host.
			host is too long. (With memory link)		Increase transmission interval.
			Command transmission to the host		Check the communication cable.
			is not possible.		Check the control method at the PT and the host.
					Increase the communication on speed when it to
					slow.
7-3		Maintenance of the NT31/NT31C
				Carry out maintenance work in order to ensure that the NT31/NT31C is always
				used in its optimum condition.
					WARNING
				Do not attempt to take the unit apart and do not touch any inter-
				nal parts while the power is being supplied. Doing either of
				these may result in electrical shock.
Spare PT
				It is advisable to have a spare NT31/NT31C available to minimize system down-
				time in the event of an NT31/NT31C failure or if the screen display becomes diffi-
				cult to read due to deterioration of the display unit.
Backlight				When the backlight in the display is getting dim and the screen cannot be read
				easily, replace the backlight. The backlight can be replaced at the rear of the
				NT31/NT31C while it is mounted in an operation panel.

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